EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: Simon on August 04, 2012, 11:37:54 am
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Right following on from a very informative discussion about air flow rates into a car engine I have a new problem. My Fiesta MK4 ECU has decided to no longer turn the radiator fan on. I have been to a mechanic and we have checked. He was able to make the fan run by instructing it to via his diagnostics machine and he as I is getting temperature readings from the diagnostics bus. So somewhere in the ECU it has decided to no longer turn the fan on. I am rather perturbed by this as clearly it is not just a blown output transistor as he got it to work via the ecu with manual instruction and the requuired information is coming in. It's like the things programming has changed.
I don't know if it is relevant but a few miles prior to this problem being discovered (on being stuck in traffic) my engine suddenly started running more smoothly and with less petrol (I had a few miles back accelerated to 3700 rpm which I rarely do so might of shook some rubbish out somewhere ?). Is it possible that the ecu reprogrammed to account for a change in the engine condition and forgot it has to activate the fan ? or has something burnt out. I am puzzled as the information is going in and it can be made to actuate the fan but it chooses not to.
He said I can have it sent away and fixed for about £200, but as this point I wonder, should I just get a new one, it's 12 years old, will anything else in it fail. Or is it a program fault. Educate me on ECU's :P
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Are you 100% sure the ECU controls the cooling fan?
In some setups the fan has its own temp switch. If that switch fails the fan wont engage.
Regards
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yes it does, checked the diagrams and we instructed it to turn the fan on so it definitely controls the fan.
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One trick that can fix errors like this is to disconnect the battery for about 24hours. This clears the memory, when you reconnect the battery and start the car it will reset to default settings.
Regards
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hm worth a try, 24 hours ? that's going to be difficult.
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Then again, if the car is running better, just rig up a fan controller and leave the ECU alone......
Regards
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my concern is that if it is a physical problem more might go wrong. A good reset should do no more harm. Yes the mechanic suggested I make my own controller.
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At first, i would try to "manually trigger" the the fan. If you already got the schematics, you should know which wire has to be (usually) pulled to ground in order to activate things. BTW: usually it is not the engine ECU which is controlling the fan(s), but if you say so, it may be.
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The ecu controls the fan relay. We plugged a diagnostics machine in and told it to run the fan and it did. So I conclude the ecu can actuate the fan if it wants to.
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Ok. Try to activate the relay somehow (without the ecu), if it is working you should check the harness and if that is ok too, it may be the ecu. Also check for the (positive) supply for the fan/relay too (wiring, fuse, etc).
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your not listening, the whole fan actuation circuit works, from the fan right back to the ecu because we made the fan run manually, and whats more we did it through on the diagnostics line of the ecu so even the output stage that actuates the relay works in the ecu.
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your not listening, the whole fan actuation circuit works, from the fan right back to the ecu because we made the fan run manually, and whats more we did it through on the diagnostics line of the ecu so even the output stage that actuates the relay works in the ecu.
Ah sorry, you're right. I missed that you could start it manually. If the hw is working, no idea then.
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Simon,
these people may be able to help more.
Fiestaguides.co.uk (http://Fiestaguides.co.uk)
Some info here as well.
http://uk.answers.yahoo.com/question/index?qid=20120323060644AAzcEE2 (http://uk.answers.yahoo.com/question/index?qid=20120323060644AAzcEE2)
Regards
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How about the engine coolant temp sensor?
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Sometimes, that fan is controlled by the ECU as well as by a standard temp control loop. The ECU control is for aircon, with the A/C on the ECU triggers the radiator fan at certain (near idle) engine speeds to improve cooling. Not saying this is the case here, but there could be a side by side control for the fan.
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How about the engine coolant temp sensor?
that works fine, my permanent diagnostics panel is reading the temp fine. so info is going in, fan can work, but it wont.
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Sometimes, that fan is controlled by the ECU as well as by a standard temp control loop. The ECU control is for aircon, with the A/C on the ECU triggers the radiator fan at certain (near idle) engine speeds to improve cooling. Not saying this is the case here, but there could be a side by side control for the fan.
This makes more sense to me.
Regards
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Sometimes, that fan is controlled by the ECU as well as by a standard temp control loop. The ECU control is for aircon, with the A/C on the ECU triggers the radiator fan at certain (near idle) engine speeds to improve cooling. Not saying this is the case here, but there could be a side by side control for the fan.
according to the schematics the ecu directly controls the fan relay, nothing else. There is no air con on this car and it's the basic model.
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Sometimes, that fan is controlled by the ECU as well as by a standard temp control loop. The ECU control is for aircon, with the A/C on the ECU triggers the radiator fan at certain (near idle) engine speeds to improve cooling. Not saying this is the case here, but there could be a side by side control for the fan.
This makes more sense to me.
Regards
This makes sense if you have air con as the air condenser also needs air throught it from the same fan.
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All i can say is check out http://fiestaguides.co.uk/ (http://fiestaguides.co.uk/) .Someone else must have had this issue at some stage in the last 12 years.
Regards
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I had a similar problem on a Vauxhall Combo van one hot summers day I got stuck in traffic and found the radiator fan would not work and had to drive home with the heater on to stop the engine boiling. I checked the fan it worked I replaced the sensor switch still no fan when the engine got hot I put both the old and new sensors into boiling water both worked, I heated the sensor while in circuit on the van but not screwed into the radiator the fan came on, so I cleaned out the radiator still no joy so I went the main dealer. I was told that this is a common problem most people don't notice it , It is a design fault the sensor is at the bottom of the radiator not the top and the coolant stratifies leaving hot at the top and cold at the bottom particulary a problem at low revs, slow speeds and with a water pump that is not working correctly. I fitted a new water pump and the fan would come on.
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my sensor is in the block, sounds like the radiator was a bad design, should have been a mutipass
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Not so sure how easy it would be to reflash the firmware (or even obtain it) but that would be one way of ruling out firmware corruption, provided it is a flash MCU and not mask ROM/OTP (which is a lot less prone to corruption).
The ECU probably has analog circuitry and electrolytic caps, the latter are known to fail.
Or it could be something as trivial as a solder joint that's cracked from vibration.
Unless the fan output is really directly controlled by the MCU there are other things to go wrong.
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my sensor is in the block, sounds like the radiator was a bad design, should have been a mutipass
Are you sure the sensor for the radiator fan is in the block, the one in the block is usually the engine temp. sensor with another in the radiator for fan control as the engine is often hotter than the radiator and with the fan controlled from the engine block you can have it turning on when not required in the winter when the thermostat is keeping the engine hot but the radiator is cold.
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my sensor is in the block, sounds like the radiator was a bad design, should have been a mutipass
Are you sure the sensor for the radiator fan is in the block, the one in the block is usually the engine temp. sensor with another in the radiator for fan control as the engine is often hotter than the radiator and with the fan controlled from the engine block you can have it turning on when not required in the winter when the thermostat is keeping the engine hot but the radiator is cold.
I expect it is near a water channel or pokes into one. the fan control comes from the ecu we know that for certain, there is no other circuitry that I know of that controls it.
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Hello,
If only you had a Rover or a MG, I would have been able to help you more.
The car ECUs are usually well designed and they requires a good knowledge about the specific engine management unit.
The decision to turn the fan on is usually made by the ECU on sensor inputs (can be the coolant temperature sensor, or an engine bay temperature sensor) or following an algorithm (car speed vs. coolant temperature vs. external temperature). Effective debugging is only possible if you know the algorithm and you can act on a sensor.
Are you sure that there is something wrong with your car? The fan should be on only in specific cases.
In any case, the paramount test is to leave the car running while stationary, for a good 20-30 minutes. At some point, the coolant fan should turn on.
If the fan always stays off and the coolant temperature starts to be higher than usual, then yes, there is something wrong. Otherwise, I would say that everything is OK.
Cheers,
Dan
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well we nearly boiled over while in still traffic. I have got the engine coolant to 100C and the fan won't come on.
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I used to own a Fordza (Mazda badges but ford internals) and they all have a thermoswitch on the left side of the radiator, about half way down. Might be covered with a cowling and hidden by a battery, but is there. Normally it, or the fuse associated with it, fails. Changed a few on assorted Fords over the years, as they are a common failure. SA is a small market, so the UK fordza mechanicals are often used here in the assembly line ( and are exported to the UK as well)so there is most likely a hidden thermoswitch. ask any motor factor, or get the electronic version of Haynes or Chilterns for your model. Otherwise go to an agent and ask at the spares division to look it up on the microfiche. Then grab that 27mm AF spanner and change it.
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no electrics on the rad at all. there is not much cowling but for what is built into the square fan.
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Not even on the sides? If it is built into the ECU then disconnect the battery, turn on the headlights and leave the door open for 15 minutes. This will deplete the keep alive memory capacitor in the EMU and the airbag controller ( lights on and door open is so that there is a resistive load across the unswitched battery bus to make sure) so that they will restart with the default values. Will lose the edaption values, though, so you will need to take a long drive again to relearn them.
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nope no electrics at all. putting sensors into radiators is extra expense and complicates things, the radiator tanks are plastic, very cheap design, we'd buy that rad for about £30 at work, easier to just screw it into the engine. The rad thermostat comes in at 88C and the fan should come on around 98C so some leeway. The fan does not even blow on the whole rad, just half including the area covered by the "shroud"
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It would be a good project to get an ECU 'running' on the bench, with all analog sensor inputs to the ECU generated by a microcontroller. We looked at doing this with a Mazda/Ford ECU but after counting 17 sensors, some 10 actuators, and scant documentation on any of them, the idea was soon abandoned!
In the Ford/Mazda workshop manual, it was ever so vague.. "sensor X should measure between 0.20v and 1.58v" etc.. e.g. no proper explanation of the role of any of the sensors, their transfer functions, nor how the sampled analog data was actually used by the ECU.
The CPU in that particular 1996 Mazda ECU was a 68HC11, an 8-bit microcontroller from Freescale, powered by the Motorola 6800 microprocessor. [1] The firmware was held in a 256Mbit serial EEPROM. In theory, the firmware could be extracted and run in a processor emulation environment on a PC (in QEMU or similar). [2]
ECUs are the quintessential 'black box' device. They have inputs, they have outputs, but what goes on inside remains top-secret!
cheers, a
[1] http://en.wikipedia.org/wiki/Freescale_68HC11 (http://en.wikipedia.org/wiki/Freescale_68HC11)
[2] http://wiki.qemu.org/Main_Page (http://wiki.qemu.org/Main_Page)
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Just read the whole thread. I would think the ECU is the least likely place to look for a fault. It is solid state electronics with no moving parts. There is nothing to go wrong.
What you have is a control loop. The engine/coolant temperature is measured in one or more places, this measurement is fed into the ECU, the ECU decides when to turn the fan on.
You have verified that the output part of the control loop from the ECU to the fan works OK. But have you verified that the input part from the temperature sensor to the ECU is working correctly? Using the diagnostic computer is there a way to get a readout on the temperature seen by the ECU?
One thing I would do is physically check the temperature sensor circuit. Make sure the sensor is working and that all electrical connections are sound between the sensor and the ECU. You could unplug wires and clean terminals with deoxit and/or fine abrasive. Put a meter on the temperature sensor itself and check that it is sending out the right signal.
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can you back-probe all the sensors that are used by the ECU to determine fan activation? What is the diagnostic interface like on the Mk.4 Fiesta? Can it diagnose a failed sensor circuit?
cheers, a
EDIT: ianb (with the funny hair) has pretty much said just that :)
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I don't know if there are more sensors. The haynes manual was written by two faced bastards who specialize in making things as clear as mud but covering the ground. My book covers 5 models all with different engines. I will have to go though all the partial diagrams and see if i can spot any other sensors. As things stand now the break in the loop is the ECU, it knows the coolant temperature because it is telling me it on the diagnostics line, it can make the fan work if it wants to because we made it do it.
I will study the diagrams in detail, see what I can find. Ideally a large printed diagram of the whole car should be included with these books, one per model, the array of partial schematics with details for multiple models is just stupid.
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Maybe the coolant temp. sensor works to a point, so it passes initial tests but fails once the coolant has got hotter?
Dunno who produced this manual, but there are some wiring diagrams at the back for the various engines used in the Mk.IV. See page 250 onwards.
https://rapidshare.com/#!download|668tl2|362825041|Ford_Fiesta_1995_Service_and_Repair_Manual.pdf (https://rapidshare.com/#!download|668tl2|362825041|Ford_Fiesta_1995_Service_and_Repair_Manual.pdf)
EDIT: Or maybe this one?
http://thepiratebay.se/torrent/4922665/ (http://thepiratebay.se/torrent/4922665/)
I'm sure there used to be an official DVD with Ford workshop manuals for most/all Ford models up to 2004, or some such.
cheers, a
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Thanks, will take a look when I'm on a pc. I've gone through the relative schematics in the Haynes manual and can only find 1 coolant temp sensor.
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It wouldn't surprise me if the Haynes manual was wrong, especially covering several different versions of your car. All the Haynes manuals I've ever had to look at have always been a let down in the circuit diagram/description area.
I think they feel that mechanics don't/can't use this information anyway.
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Haynes are hit and miss. One copy I have have diagrams that are largely useless while another for a different model not only has accurate diagrams but in them has illustrations of all the connectors.
One of my cars has three temp sensors, one for the fan, one for the ecu and one for the dash gauge!
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I think Haynes should be ashamed of themselves. They have gone from high quality to con merchantry. Non of their texts make sense anymore or are practical. Clearly not written from hands on experience - bunch of wankers !
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Hey Simon
I had a quick look at the wiring diagrams and there appears to be 2 temp sensors but that of course depends on the engine.
I'm guessing thermistors but you'd have to meter them to know for sure. In any case I'd disconnect one then the other and see if you get an engine warning light. You should also be able to ID the one that is for the instrument gauge. I know you had it connected up to a diagnostic tool, did it give the temp of the engine?
As for the ecu controlling the fan that is certainly not in the diagram. You could get item 8 in the diagram and wire up the fan in the same way.
Regardless of what you do a switch applying power to the fan will keep the motor from getting damaged. Of course you will have to take the place of the computer. I guess that would be a biologically enhanced car. I unfortunately have had several of them (but only until fixed properly).
...mike
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"The electric cooling fan, mounted behind the radiator, is controlled by a thermostatic switch. At a predetermined coolant temperature, the switch contacts close, thus actuating the fan."
If you don't have wires coming off your radiator, well, you should. The ECU needs control of the fan for AC &/or Turbo. Since you don't have either, you could wire the switch directly to the relay (if it isn't like that already). My bet is on a failed radiator thermal switch.
http://www.ebay.co.uk/sch/i.html?_nkw=ford+fiesta+radiator+switch (http://www.ebay.co.uk/sch/i.html?_nkw=ford+fiesta+radiator+switch)
-sj
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Simon
There are two temperature sending units in your car, find them. One could be labled as a temp switch, fan switch, or whatever the hell they decided to name it. I have seen those sensors on the coolant return from the radiator, down on the bottom of the engine block, it could be anywhere, you gotta hunt for it.
Also look for a BAD GROUNDS, from battery to chassis to engine to dash. After you said that it started running better and then the cooling fan quit, I would really start looking for BAD GROUNDS! Most sensors rely on chassis/engine ground and 5VDC from the ECM to send their signal back to the ECM in a voltage range that it can understand. It is also possible that you have a short to ground or a heavy current draw on that 5VDC line from the ECM. That will create all sorts of strange behavior that is hard to track down. A sensor that is leaky or intermittently shorting to ground or opening up putting 5VDC on the sense line back to the ECU could keep it from knowing when to turn on the engine fan.
Check ALL fuses and links with an ohmmeter to insure that they are not blown. Please don't trust any schematic, manual or diagram, they are likely all wrong. Verify by chasing the harness to the very end connectors and make sure there is no pinches, chafing, burns or missing insulation. Change out the cooling fan relay for a known good one, never trust, verify operation or replace it. Automotive environmental conditions are hell on electronics as you know.
Good luck...
Chris
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Just talked to a mechanic friend of mine, and he reminded me that a lot of those coolant sensors are mounted in plastic blocks inline with the piping for a lot of cars. Look at the plumbing ( you may have to remove a lot of plastic trim covers to see) and look at the water piping for a black object with a connector or two coming from it. Post a photo and WE will be able to ID what the part is.
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What's the exact model of car? The 1995 service manual pointed out above does not show any ECU control of the fan.
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Fiesta mk4 2000 finesse
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EDIT: Or maybe this one?
http://thepiratebay.se/torrent/4922665/ (http://thepiratebay.se/torrent/4922665/)
I'm sure there used to be an official DVD with Ford workshop manuals for most/all Ford models up to 2004, or some such.
cheers, a
Piratebay is blocked in the uk
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Dunno who produced this manual, but there are some wiring diagrams at the back for the various engines used in the Mk.IV. See page 250 onwards.
https://rapidshare.com/#!download|668tl2|362825041|Ford_Fiesta_1995_Service_and_Repair_Manual.pdf (https://rapidshare.com/#!download|668tl2|362825041|Ford_Fiesta_1995_Service_and_Repair_Manual.pdf)
It's a sodding Haynes manual and for the MK3 I think. Has no 1.3L but a 1.4L engine and calls it HCS, this was the predecessor and basis of the endura E I have. Probably the same as my dads old ecscort from 1989
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I was having all kinds of wierd problems in my bmw with erratic idles and poor fuel economy, i pulled the ecu out on a hunch and cracked it open.
It was heavily water damaged, pins shorted on the IC's, corrosion all over the shop, its a testament to the tolerance of errors in the design that the car ran at all.
I was able to score a second hand one on ebay for about 70 pounds + 10 pounds postage, a lot of the different models of ecu are shared between makes of cars, you just need to transfer the rom that stores the program for your car from your old one to the new one.
So it might just be worth replacing the thing.
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the ecu for mine i think does the MK3, 4 and escort MK6. It is I think in the passenger aread behind the facia so should be protected fro water. Where on earth did they put the BMW ecu ?
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Many cars have it under the bonnet, usually beside the engine.
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Many cars have it under the bonnet, usually beside the engine.
pretty stupid place, haven't forgotten when my dads escort engine flooded because we ran into deep water the ecu would have gone with it, we dried the engine out but an ecu would not have come out well.
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My ECU is on the top side of the engine, if it is flooded the entire engine is full of water.........
If you do get another ECU you will need the keys as well, as they have a transponder that is interrogated by the ECU at power up and randomly thereafter. No match no go, unless you leave the power on for 4 hours, when the ECU will go into limp home mode and ignore the key transponder code.
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Piratebay is blocked in the uk
No problem here, pal. Check your P.M.
I can try to find the diagram for your car, but I need the exact year and model, including engine type (i.e. 1.25 16V DHD).
Possible causes for that fault:
- you have more than one temp sensor, one for dash and one for ECU
- you have just one temp sensor; good wiring between dash and sensor, but bad wiring between ECU and sensor
- faulty ECU (seen that, been there)
Give me your model and we will try to find out about sensors.
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Fiesta finesse, 2000 Endura E engine.
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Fiesta finesse, 2000 Endura E engine.
Is it 1.3 or 1.4 liter model? 1.4 is 16 valve. And what about horsepower?
There's a dozen of those engines, sorry...
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1.3L I think 60 BHP
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1.3L I think 60 BHP
Then it's J4L or J4J engine. Please P.M. your e-mail address - I've got the wiring diagrams for your car.
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Here's a short troubleshooting guide:
- turn ignition on
- check the voltage between battery ground and pin 46 of ECU connector. it should be 0 V
- check the voltage between battery ground and pin 7 of ECU connector at room temp (20?). it should be 2.9-3.1 V
- check the voltage between battery ground and pin 7 of ECU connector at 80?. it should be 0.7-0.9 V
- let as know of the result
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pretty stupid place, haven't forgotten when my dads escort engine flooded because we ran into deep water the ecu would have gone with it, we dried the engine out but an ecu would not have come out well.
that's why 80% of Russian-made vehicles have ECUs inside the cabin, under passenger's feet.
doesn't help much, though. :)
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Russian vehicles, built cheap and easy to repair. Really good heaters though...... Add as well a rear window demister, so your hands don't get cold pushing it.....;)
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Russian vehicles, built cheap and easy to repair. Really good heaters though...... Add as well a rear window demister, so your hands don't get cold pushing it.....;)
The only one I really like is Lada 4x4 http://en.wikipedia.org/wiki/Lada_4x4 (http://en.wikipedia.org/wiki/Lada_4x4)
It's a real beast when offroad. And it's a pain in the butt on the road.
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All this reinforcement of "Found On Road Dead" or "Fix Or Repair Daily" is depressing. May I suggest your next car is a Honda?
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I have had a Ford, very nice vehicle and easy to fix. Only time it died on the road I had a spare ignition module ready, known failure, and it was a pirate one anyway, so I had bought 2 for $5 anyhow..
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May I suggest your next car is a Honda?
Why not Subaru? Those beasts are insanely reliable. A friend of mine has Honda CR-V, and his wife has Subaru Forester. They live in a desert area, so just one failure can cost you a lot by means of your health and life. He literally calls her car "an ass-saviour".
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Given the number of people I know who have had big problems with recently made Japanese cars, I wouldn't touch them with a bargepole. Much of the reputation of these companies is down to skewed reliability data as they tend to be self-reported in voluntary surveys. What it usually boils down to, is that cars used by retired people who don't drive much are apparently really reliable, and cars used every day to drive across fields are unreliable. Who knew?
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All this reinforcement of "Found On Road Dead" or "Fix Or Repair Daily" is depressing. May I suggest your next car is a Honda?
I own a Ford and a Lexus (Toyota). My wife owns a Honda. All are from the late 1990s. All have been reliable and mostly trouble-free. Ford is at ~140k miles, Lexus is around 116k, Honda is almost 200k. OEM Parts for the Ford and Honda are pretty inexpensive. Lexus parts are very expensive, though a better deal can be had by finding the Toyota equivalent. Both Ford and Honda have lots of aftermarket repair parts -- Lexus, not so much. The Lexus has had far fewer annoying problems than the other two (except for the stereo -- even with the Nakamichi option, the speakers are crap). The Ford has structural rust; the Lexus and Honda do not. The paint on the Ford is peeling off of the primer (yes, it is the original paint). The clearcoat on the Honda is failing.
None of the vehicles requires than $1000/year on average for repair and maintenance, so I'd say that they all do pretty well in that respect.
I used to have a Nisssan. That car was great, except for rust! Had one failed starter -- and no other major mechanical issues in 14 years and 198,000 miles.
This reminds me of some jokes:
What do you call 6 Chevys and a Ford? A junkyard and a ride home!
Nine out of 10 Chevys made in the last 10 years are still on the road. The rest made it home.
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I would think the ECU is the least likely place to look for a fault. It is solid state electronics with no moving parts. There is nothing to go wrong.
A few years ago I had to use a pic 16f84a to replace the entire indicator system in a Peugeot 206 because of a failed blackbox. I was so angry with the rip-off price of a new box and the fact that there was no documentation that i was determined to make it work. I bypassed the box for the left, right and hazzard switches, then wrote some code to handle the logic; It worked a treat! You could potentially replace the blackbox and the ecu given enough time and effort. It was certainly not worth it for my crappy 206 though but if you had a nice car you might fancy it.
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You could potentially replace the blackbox and the ecu given enough time and effort.
It's not that simple. There are several Russian wizards who make custom-made firmwares for ECUs. It's rather expensive because of all the equipment they use. And it's very complicated, because there is still no reliable scientific model for internal combustion engine. At least half of the parameters in the ECU are not calculated, they are based on experiments on the exact engine. I know several guys who make so-called "chip-tuning". Basically, what they are doing, is they take your car and your ECU and try to get better parameters for ECU firmware. Sometimes they replace the firmware completely. One could get 20-30 hp more after that procedure.
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You could potentially replace the blackbox and the ecu given enough time and effort.
It's not that simple.
My crappy Peugeot 206 1.9 D LX, 2000 year plate was pretty simple as there wasn't much to it, a few sensors etc. I got a ecu and blackbox from a scrap yard and ebay for next to nothing and ripped them apart to study them and did a lot of research, but like I say mine was a simple car, but from what you say it appears it's more difficult for more complex systems, the biggest problem for me was lack of documentation.
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if you already have the schematic and yet still unable to figure out whats going on, i suggest bypassing the fan and temp sensor and make your own FCU (fan controller unit). btw, does anybody know or have ECU schematics for toyota wish car 1.8cc 2003 make?
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btw, does anybody know or have ECU schematics for toyota wish car 1.8cc 2003 make?
ECU schematics? You are dreaming.
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Many cars have it under the bonnet, usually beside the engine.
In the Peugeot 206 I looked at, there was an ECU (blackbox) by the engine and another blackbox under the steering column. The later Blackbox handled all the non-engine related stuff, including the fan, display, light, indicators, odb etc
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btw, does anybody know or have ECU schematics for toyota wish car 1.8cc 2003 make?
ECU schematics? You are dreaming.
coz i wonder, if i translated it correctly i read people have their car's ecu schematics (fan controller section) in early page. ;) (i havent read all pages through)
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ECU schematics? You are dreaming.
coz i wonder, if i translated it correctly i read people have their car's ecu schematics (fan controller section) in early page. ;)
Nope. It's vehicle wiring. What's inside ECU - is a well-kept secret. Never seen a full schematics, although there's nothing hi-tech.
Some manufacturers even go so far that they order ICs with their's own markings. And instead of original IC name like NE555 you will get something weird like J25. Good luck seeking a datasheet.
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Just some (not so relevant) comments:
There is a world of difference between the Engine Management Unit (EMS) or (improperly called) Engine Control Unit (ECU) or Powertrain Control Module (PCM) and other Electronic Control Units boxes.
The lesser ECUs will manage auxiliary functions such as ABS, safety features (locking, windows, engine immobilization), suspension (if active), entertainment units, etc.
As jucole attested, a dedicated and resourceful person can be able to repair, improve or even duplicate the ECU boxes.
However, I highly doubt that the core functionality of the EMS unit is easy to be tackled at hobbyist level. Not because of the complexity of the task, most EMS are just a processor (with rich input/output features) with its subsystems and adequate output drivers. The EMS reads sensor inputs and drive a lot of actuators according to some pre-programmed Look-Up Tables (Maps). The difficulty resides in the fact that it's impossible to do anything remotely useful if you don't have an understanding of the physics of the engine and the impact of your actions. It's just not feasible. You should have some ways to observe the engine behavior (problems, performance) and counter-measures to highly dangerous situations (engine knocking, blowing, catching fire, etc).
There are some "generic" or Aftermarket Engine Management Units, but these are the result of quite expert people working hard.
Cheers,
Dan
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Nope. It's vehicle wiring. What's inside ECU - is a well-kept secret. Never seen a full schematics, although there's nothing hi-tech.
Depends on what you call hightech and and what vendor/car you look at. But a state of the art ECU can be pretty sophisticated.
Some manufacturers even go so far that they order ICs with their's own markings. And instead of original IC name like NE555 you will get something weird like J25. Good luck seeking a datasheet.
Not just markings. ECU vendors use their own ASICs and the CPUs can be also variants that are not available on the free market (e.g. stripped down or advanced versions of generally available base versions).
As a side note: hints uttered here like disconnecting the battery for 24h hours are (most probably) pretty much pointless. There are only a few ECUs which use a RAM with permanent supply. Volatile data is usually stored in SRAM and lost within seconds after disconnecting the battery and after the capacitors discharged (which usually doesn't take very long). Nonvolatile data is stored in EEPROM (old school) or flash (typical nowadays) and therefore won't get lost by removing the battery. Besides when removing the battery there is alway a slight chance that the nonvolatile memory gets corrupted, so be careful with this and do it only some minutes after switching off ignition/accessory.
If a component is deactivated due to a stored fault this can usually be either cleared by a normal power off cycle (if it's just temporary) or only by means of an OBD2 device (if it's critical). No need to disconnect the battery.
Then again, when a critical component like the fan is deactivated due to a electrical fault, chances are that the engine will only run in some kind of limp home mode. But this is vendor specific of course.
Anyway I still would suspect that some temperature sensor is defective. Note that there might be multiple temperatures like oil temperature, coolant temperature, engine temperature, air temperature. The fan is usually controlled via the coolant temperature, but you never know what people come up with. Usually a defective sensor should be detected by the ECU and reported via OBD2. Then again, if it's weirdly floating or it's a dumb ECU, it might as well not recognize the sensor defect.
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it remains a mystery. Will have a poke around with my diagnostics panel later when I'm hoe from my work course. Not sure what it can do though as it's only basic. I'm certainly not in limp home mode, engine is performing better than it ever has with record low fuel consumption. Have driven up to 70mph and high revs (4300 rpm) with no problems.
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There is a world of difference between the Engine Management Unit (EMS) or (improperly called) Engine Control Unit (ECU)
Why do you consider it improper?
As jucole attested, a dedicated and resourceful person can be able to repair, improve or even duplicate the ECU boxes.
Repair? Sure. Did that, been there. Sometimes it's damn hard to solder (check out so-called Chip-On-Board type), but I did that.
Improve? Doubt it.
Duplicate? Next to impossible in terms of equipment and man-hours.
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Depends on what you call hightech and and what vendor/car you look at. But a state of the art ECU can be pretty sophisticated.
Usually it's just an 8-bit microcontroller running at 16/20 MHz, EEPROM, a couple of MOSFET arrays, and (maybe) ADC. No state-of-the-art fancy ICs, no FPGAs. BTW, never seen an ASIC inside. Did you?
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Have driven up to 70mph and high revs (4300 rpm) with no problems.
So, does that mean that you problem with the fan is gone?
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Post some photos of the engine, with the water piping shown.
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Have driven up to 70mph and high revs (4300 rpm) with no problems.
So, does that mean that you problem with the fan is gone?
No not that I'm aware of but just saying that the engine is running fine so doubt the ECU is in limp home mode, engine couldn't be running better. But as far as I know the ECU won't cut the fan in.
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Post some photos of the engine, with the water piping shown.
not easy at the moment, what am I looking for ? it's a cheap two pass radiator with plastic tanks and a rather thin core (I've seen air con condensers that thin lol). There are no sensors on the radiator or on the pipework close by, maybe further back I grant you but no sign of them on the diagrams and the fan is definitely activated by the ecu as we did it manually.
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Normally next to the engine. The locally made vehicles are sufficiently different to the UK ones ( same kent derived indian made engine but modified for the ambient high temps and altitude changes) that the build is totally different. Not the radiator but the engine bay, looking to the back and down, from the sides and from the back looking down.
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No not that I'm aware of but just saying that the engine is running fine so doubt the ECU is in limp home mode
If there is no C.E. light, it's definitely not in a limp home.
Still waiting for your measurements for fixin' ya car then. ;)
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No not that I'm aware of but just saying that the engine is running fine so doubt the ECU is in limp home mode
If there is no C.E. light, it's definitely not in a limp home.
Still waiting for your measurements for fixin' ya car then. ;)
hopefully this weekend, I don't think the hotel I'm staying at will appreciate me taking my carto bits in their yard or overstaying my welcome ;)
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Depends on what you call hightech and and what vendor/car you look at. But a state of the art ECU can be pretty sophisticated.
Usually it's just an 8-bit microcontroller running at 16/20 MHz, EEPROM, a couple of MOSFET arrays, and (maybe) ADC. No state-of-the-art fancy ICs, no FPGAs. BTW, never seen an ASIC inside. Did you?
Even >13 years ago my very first ECU project had a 32bit CPU. The low end stuff was done with 16bit Controllers until a few years ago, but nowadays it's all 32bit, even in the very small three cylinder engines. On the high end side, there's e.g. a 256MHz CPU with nearly 500 pins (BGA) and the next step is dual core. Plenty of ASICs as well of course. More than 10 in one of the bigger projects. Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.
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Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.
As far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?
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There is a world of difference between the Engine Management Unit (EMS) or (improperly called) Engine Control Unit (ECU)
Why do you consider it improper?
Because (at least in my experience), the ECU name is usually reserved to (lesser) Electronic Control Units, while the Engine box should be always called EMS or PCM.
As jucole attested, a dedicated and resourceful person can be able to repair, improve or even duplicate the ECU boxes.
Repair? Sure. Did that, been there. Sometimes it's damn hard to solder (check out so-called Chip-On-Board type), but I did that.
Improve? Doubt it.
Duplicate? Next to impossible in terms of equipment and man-hours.
Exactly my point. I was talking in this context about the (lesser) ECU boxes, while acknowledging in the next paragraph the difficulty of working with EMS boxes.
Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.
As far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?
There are several ARM-based products from Samsung. There are automotive chips, in the sense that there are very well equipped with serial and parallel I/Os, watchdogs, counters, DACs, ADCs, PWM, whatever makes sense in the automotive I guess.
A few examples are the following:
- ARM7TDMI-based: a few S3F4A*** such as S3F4A1HR, S3F4A2FR, etc
- Cortex-M3: S3FMA1U, S3FMA1G
The ARM core (and its wonderful JTAG bus) makes the chip instantly familiar to a lot of programmers (software and hardware). You just need to concentrate on the extended I/O features to make them do whatever you want.
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Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.
As far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?
Yes. Dont forget about the siemens c166/167 on 16mhz either. They also used two of these in conjunction for six cylinder engines.
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Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.
As far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?
Most if not All ECUs from BMW, Audi, Porsche etc. in the last ~10 years used e.g. TriCore CPUs (TC17xx) from Infineon or Oak/eSys CPUs from Motorola/Freescale. Even before that, the Hitachi SH7055 was used here and there. In the last few years, also a lot of VW/Skoda/Seat ECUs use 32bit ECUs (mostly TriCore, some eSys). Modern GM ECUs use large FSL eSys CPUs as Viper, Copperhead, Mamba and Cobra. At least the larger ones of these CPUs are BGA.
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Most if not All ECUs from BMW, Audi, Porsche etc. in the last ~10 years used e.g. TriCore CPUs (TC17xx) from Infineon or Oak/eSys CPUs from Motorola/Freescale. Even before that, the Hitachi SH7055 was used here and there. In the last few years, also a lot of VW/Skoda/Seat ECUs use 32bit ECUs (mostly TriCore, some eSys). Modern GM ECUs use large FSL eSys CPUs as Viper, Copperhead, Mamba and Cobra. At least the larger ones of these CPUs are BGA.
Nice! Do you fix or make those?
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Here's a picture of the internals of an Audi Q5 ECU:
(http://www.tuningworld.com.au/gallery/wp-content/uploads/2012/07/Audi-Q5-3.0-TDI-White-Kraftwerk-Open-ECU-Tuning-Ramspeed-Automotive-4.jpg?9d7bd4)
I guess it'll be common across the range.
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Nice! Do you fix or make those?
I work for one of the biggest suppliers, so we develop ECUs (HW and SW).
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I work for one of the biggest suppliers, so we develop ECUs (HW and SW).
cool stuff!! - just out of interest how much input protection is there from the sensors etc on early thru to today's ECUs (HW and SW),? are they easy to mess up?
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ECUs are supposed to be more or less idiot-proof. Stuff like reverse polarity, loss of ground and applying battery voltage or ground to every pin without damage is to be expected even for low end stuff.
Depending on the level of protection that a customer requires, there might be also ESD protection for CAN etc.
However a normal input pin is usually only protected by serial resistor and (CPU internal) clamping diode.
Outputs are usually provided by specific ASICs (e.g. fully integrated H-bridge or highside/lowside drivers) which implement full diagnosis (at least open load, short circuit to ground, short circuit to battery) and self protection.
Anyway, I don't think the protection strategies changed that much during the last decade. Just the diagnostic capabilities increased a bit due to stricter requirements.
On SW side, you can expect that there is very detailed diagnosis available inside the ECU (e.g. also stuck/inplausible values for sensors) and with modern ECUs,
the number and detail level of diagnosis reported to external testers has increased quite a bit. But of course, it will be alway a condensed and simplified version of the information available internally.
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Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.
GM used 8 bit for many many years, in Oz we had a HC11 variant based ECU and PCM until changing to a Bosch in 2004 on the locally built V6, the same car but with a V8 went to a 32bit 68k Delphi PCM in 2000 after running the same HC11 prior. We first got them in 1988 using a secondary ASIC. From 1994 it controlled engine and trans but on different hardware. It was all US developed hardware and firmware with aussie engineers doing the engine calibration here. Its a simple processor with well written assembly so has been a hacker and DIY users dream, we have added all sorts of stuff to the code. 8)
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is there any chance that ignition interference can cause issues, the mechanic said he has had some in the past. Not sure if he was referring to ignition wrecking other stuff or the ignition drivers breaking due to the ignition hardware driven. I think for cheapness most stuff is all in one ecu on my car.
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is there any chance that ignition interference can cause issues
Never saw one. Read about some issues with Ford Mustang's, whose camshaft position sensor had problems due to EMI.
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I was thinking more damage done by say related back e.m.f. over time or maybe extra strong due to some extra revving ?
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Not likely, the normal failure mode of the sensors is the sensor dies, not the management unit.
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Here's a short troubleshooting guide:
- turn ignition on
- check the voltage between battery ground and pin 46 of ECU connector. it should be 0 V
- check the voltage between battery ground and pin 7 of ECU connector at room temp (20?). it should be 2.9-3.1 V
- check the voltage between battery ground and pin 7 of ECU connector at 80?. it should be 0.7-0.9 V
- let as know of the result
I'm quite interested to see what this turns out to be. I'll put my money on either the temp sensor or a bad connection to the ecu box.
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but the mystery is how can the diagnostics bus be providing a sensor reading if it's broke or the connection is faulty. The only other explanation is a second sensor and control circuit that is totally undocumented while the ecu is perfectly capable of running the fan as we found so that makes no sense...... I'll try and find the sensor when I get back over the weekend, but as the diagnostics bus gives a sensor voltage don't hold your breath on it being the sensor.
Does anyone know the cut in temp for the rad fan on a fiesta MK4 1.3L finesse ? I need to run the engine up to that for testing but want to keep as far from engine burn up temperature as possible.
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Does anyone know the cut in temp for the rad fan on a fiesta MK4 1.3L finesse ? I need to run the engine up to that for testing but want to keep as far from engine burn up temperature as possible.
can't tell for fiesta, but it's 97-108 C for the majority of cars. of course, it's the coolant temp. engine is up to 3500C inside and on the surface - it depends on the exact place.
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well I'm talking coolant temp, at 101C the diagnostics says it's overheating but it may be over reacting to save the engine ?
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Dunno about Ford, but usually the fan should kick in at 90-100°C. Let's say around 95°C. 100°C without a fan hints towards a defective thermostat if the fan itself is working via obd.
Are you sure the temperature read via obd is really the coolant temperature? This could be also the oil temperature or whatever.
If you locate the thermostat for the coolant temperature, you could try to remove it and see if the temperature changes. Or use coolant spray or a heat gun on it and see if the temperature changes.
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Or just simply measure resistance.
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but the mystery is how can the diagnostics bus be providing a sensor reading if it's broke or the connection is faulty. The only other explanation is a second sensor and control circuit that is totally undocumented while the ecu is perfectly capable of running the fan as we found so that makes no sense...... I'll try and find the sensor when I get back over the weekend, but as the diagnostics bus gives a sensor voltage don't hold your breath on it being the sensor.
There are most commonly two or more coolant temperature sensors - one for the instrument gauge, one for the ECU, one for an auxiliary cooling fan. The one for the cooling fan is usually a switch that operates one or more fan relays directly, while the others are full range thermistors. The fan can be turned on by either by the temperature switch directly or by the ECU. Very often the only reason that the ECU has an output to the fan relay is to turn the fan on when the aircon is on. Common sense and good practice might suggest that there need only be one sensor for everything, but I haven't ever seen less than two (yet).
Wiring diagrams in Haynes and similar manuals are more of a starting point than a complete reference. Even the rest of the manual will have omissions. If you want to know for sure what your car actually has, you have to get out there and look at it. I'd keep looking for another sensor. It ought to be in the radiator or somewhere along the output of it.
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A reason to think there is a thermoswitch while the ECU has a fan output is that the range does include models with an aircon, and the wiring loom is made for the top range then installed, with only the parts omitted for the base model. This is done to keep from having 2 near identical looms in stock on the line, and allows the decision on which spec is needed to be deferred to further down the line to the point where the dashboard in inserted, rather than at the front of the line. Cost of the extra loom is minimal compared to the extra pick bin, stock shelf ( these looms are supplied on a big board neatly folded so they are not stressed during install or storage) and chances for a mixup in production.
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Dunno about Ford, but usually the fan should kick in at 90-100°C.
on a majority of Russian produced cars the fan kicks in at 103-107C. it's a NORM. and a coolant is kept under pressure to prevent it from boiling.
sometimes I think that those car's engineers have a slight form of dementia. :(
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I'm guessing that fan cut in temperature is usually about the same temp above the thermostat opening temp, so with 88-90 degree thermostat opening where does that put fan cut in ?
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I'm guessing that fan cut in temperature is usually about the same temp above the thermostat opening temp
Usually that's a different temperature. AFAIR, thermostat opens at 60-70C.
I was wrong. It's about the same temp.
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yea my thermostat opens at about 88-92C and then the temp stabilizes around 85-89C, so much cut in by 98C ?
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yea my thermostat opens at about 88-92C and then the temp stabilizes around 85-89C, so much cut in by 98C ?
if you are in a traffic jam, just opening thermostat is not enough, and temperature will go higher. then the fan will cut in.
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@Simon,
I only read part of this thread, but I would say that the ECU is NOT the problem.
I would guess its a temp sensor. get the OEM electrical schematics for your car AND THE CORRECT YEAR!!, do not use Chilton or Haynes, they are super crap, full of mistakes and very abbreviated, unreliable for electrical truobleshooting.
Many cars do have two water temp sensors check for this.
With your friend's OBD tool get into the car's realtime data, read the coolant temp, run the engine and watch the temp climb on the tool and pull the wire off the sensor, notice the change, if it doesn't the sensor is bad. Two wires are probably in the sensor connector, one is ground, (brown?) jumper the connector, read the temp.
It is possible there is another control loop outside of the ECU control. You can understand this by looking at the fan relay, for additional connections to the relay coil.
you can obtain OEM manuals from Ebay inexpensively, on DVD. Don't buy just the schematics, because they may not be of your car, but with the whole manual to read, you will know.
Get on a forum for your car and see if they can help too.