Windshield Wiper Delay Circuit

[ArTrvlr]

I am restoring/updating a '50s car that originally had vacuum operated wipers. I will be replacing the vacuum system with an aftermarket electric wiper motor. I am replacing the original steering column with one from a later model GM vehicle with the wiper switch on the turn signal lever and want to use that switch to control the new motor, including the delay or intermittent function. This is the switch:

https://m.media-amazon.com/images/I/71NNRQEHr3L._AC_SX679_.jpg

The new motor has three terminals, LO speed, HI speed and PARK.  The wiper switch has 5 delay positions, each with a different resistance value. All the wiper motor needs to make a delay cycle is a short 12V pulse to start the motor, then continuous 12V to the park terminal which will turn the motor off in the park position through the internal park switch.


I found this circuit diagram that uses the same three terminal motor (I know the title says two leads, but if you look at the motor in the diagram, it has three leads). You can see how the normally closed relay powers the park terminal whenever the switch is off. It uses a 500K pot for the delay control instead of 5 fixed resistors. I have measured the resistance through the delay settings, 1-5. (Fluke 117 meter)


1: .680 m
2: 267.9k
3: 149.5k
4: 81.5k
5: 35.9k


My questions are:
Can this circuit be adapted to work with my 5 position switch? If so, what would I change?


Is there a better way to do it? A 555 timer was suggested in my original introduction post here.


If you read that post you see I have no electronic experience. What I am looking for is help with resistor values and wattage levels for all the components. The load on the circuit will be the relay coils only. The coil load specs I have found are 150 - 160 mA.


TIA

[m3vuv]

is it speed control you want or intermitent wipe times?

[ArTrvlr]

Quote from: m3vuv on Today at 05:28:56 pm

is it speed control you want or intermitent wipe times?

Just the intermittent wipe times. The HI and LO speeds are just on/off switches.

[floobydust]

Can you give the part number or year/make, there's many different variations of Chevrolet windshield wiper motors.
The wiper motor internals - limit switches, relay, motor, park mode etc. are all over the place and that is the hardest part actually. I though Park was for luxury cars and later years.
A little circuit with 555 timer or the two-transistor circuit you posted can be made to work.
The new wand also need to know details of the wiper knob so a make/model helps there.

edit: pic of how bizarre these systems can get

[ArTrvlr]

Info requested by user bdunham7 in my intro post https://www.eevblog.com/forum/beginners/new-user-introductioninterest-feeler/
Quoting bdunham7:

"I can probably help, but I'd need to know what year/model the new steering column came from"

The steering column and switch are from a 2001 Chevy pickup. The switch is a AC Delco part number D6257C, GM # 26100839. This is the schematic of the wiper/washer system:
 8-485 Schematic-Wiper Washer Switch.pdf (495.66 kB - downloaded 127 times.)
EDIT: I did something wrong, the attachment is at the end of the message.

Again quoting bdunham7:

"as well as the technical details on the replacement wiper motor."

This is the wiring diagram for the new motor. That is the standard two speed switch that comes with the motor. The off position of the switch supplies 12 volts to the park terminal which operates the motor until the wipers return to the park position.

"The solution may be as easy as taking apart the wiper motor assembly from the steering column donor and extracting the control module circuitry."

Great minds think alike! That was my first thought and the first thing I tried.

I have the wiper motor module (GMs term for the motor with attached circuit board) from the same truck as the column and switch. I have tried to use just the circuit board (without the motor) wired to the switch as in the original vehicle. The circuit board has three terminals that plug into the motor. Bench testing shows them to be GROUND, HI speed and LO speed. I then wired the HI and LO speed outputs to relays to control the new motor. I do not yet have the new motor so used 12V bulbs to monitor the outputs, including one for the PARK circuit. HI and LO speed switch positions come on as expected. All delay positions will activate the LO speed. The problem is the circuit board is half of the park switch. The other half is a rotating contact on the motor that turns the motor off in the correct park position. Without those two halves together the motor LO terminal on the circuit board has 12V for appx. 6-10 seconds after the switch is in the off position. My guess is a timer on the board takes over. This is too much time to wait for wipers to go off and park. If this board could be modified to eliminate that delay to off, that would be my preferred solution.

Next I soldered a wire to the LO speed output of the board and ran it through a hole in the board housing so I could reassemble it and have access to the LO speed output. HI speed is a direct board trace from the HI speed switch wire to the HI speed terminal, so no extra wire needed. I wired all this up to my mock up relays and bulbs and everything worked as expected. With the internal park switch now working power is restored to the PARK circuit for the new motor any time the switch is off. For this to work in the car I would have two wiper motors, one doing switching duty and the other working the wipers. It would work but seems a really crude solution.

This is the diagram of that setup, except I used three bulbs where the new motor is shown.

[bdunham7]

If this board could be modified to eliminate that delay to off, that would be my preferred solution.

Perhaps if you modified the board so that the park detection contact was permanently grounded or live (you'd have to measure what is present at the contact coming from the motor) you could fool the board into effectively thinking that the motor was always in the park position, and that might eliminate that extended run time. 

[ArTrvlr]

If this board could be modified to eliminate that delay to off, that would be my preferred solution.

Perhaps if you modified the board so that the park detection contact was permanently grounded or live (you'd have to measure what is present at the contact coming from the motor) you could fool the board into effectively thinking that the motor was always in the park position, and that might eliminate that extended run time.

I'll open the motor back up and do some checking.

Here is the "Description and Operation" of the wiper/washer system from the GM service manual.

 8-511 Wiper Washer System.txt (4.76 kB - downloaded 43 times.)

[ArTrvlr]

Here are pictures of the circuit board in the truck wiper motor.

[brucehoult]

It seems to me that replacing a 500k pot with a series of fixed resistances with maximum 680k is probably close enough.

Given the progression of the values it seems they are used to control the charge rate, so with 680k instead of 500k the longest delay will be a little longer.

Incidentally, I HATE this style of control of intermittent wipers! Controlling the trigger point with a voltage divider is soooo much nicer because if it starts to rain harder and you want it to wipe NOW then you just turn the control until a wipe happens, and next delay will be the same as the delay up to the point you forced it to trigger.

[Circlotron]

Would have been a cool project to make the original vacuum wipers intermittent. Couple of solenoid valves and a Hall effect "home" sensor.

[floobydust]

Windshield wipers have a safety function, and pedal to the medal um oops you have pretty much nothing for vacuum.
Neighbor's '78 Corvette, the pop-up headlights are vacuum operated and um passing a car on the highway they pop down  It gets dark. Might be a problem with a leak/reservoir but the car is insane for vacuum hoses under the hood no mechanic can handle it.

OP, I can't quite follow what parts you are working with.
The new wiper motor is an aftermarket '58 Oldsmobile wiper motor from New port Engineering?
I can figure out the GM wiper pulse board but it looks like it needs a connection to the park switch.
Where are you getting "T2" from? I don't have the module's connector pinout, but see some modules use "T1,T2,T3" to connect to the motor, others are "T4,T5,T7", and the Dorman board has no labels.

[bdunham7]

Here is the "Description and Operation" of the wiper/washer system from the GM service manual.

It seems the wash function is being activated so there should be some way to hook it up differently and avoid that.

[Circlotron]

the car is insane for vacuum hoses under the hood no mechanic can handle it.

This good?
https://hips.hearstapps.com/autoweek/assets/s3fs-public/04%252520-%252520Mid-Eighties%252520Honda%252520CVCC%252520Hell%252520Boxes%252520-%252520Photo%252520by%252520Murilee%252520Martin.jpg

[ArTrvlr]

If this board could be modified to eliminate that delay to off, that would be my preferred solution.

Perhaps if you modified the board so that the park detection contact was permanently grounded or live (you'd have to measure what is present at the contact coming from the motor) you could fool the board into effectively thinking that the motor was always in the park position, and that might eliminate that extended run time.

I opened the truck motor up to check what goes on at the park contacts during operation.
This is the circuit board:

This is the disk for the park switch:

I didn't really learn much, but maybe I didn't know what to look for. The spring loaded contact that rides on the center portion of the park disk has 12 volts when the switch is off. That is normal for a park switch for it to send power through the disk to the other contact until the disk rotates to the open section in the outer wipe, parking the wipers. When the switch is in any position that calls for LO speed operation there is appx. 1.5 volts on that same contact until the 6 second timer expires then it goes back to 12 volts. I also shorted the two contacts together which, as expected, turned on LO speed.

As I said, I didn't learn anything, but maybe I am looking in the wrong place.

[ArTrvlr]

OP, I can't quite follow what parts you are working with.
The new wiper motor is an aftermarket '58 Oldsmobile wiper motor from New port Engineering?
I can figure out the GM wiper pulse board but it looks like it needs a connection to the park switch.
Where are you getting "T2" from? I don't have the module's connector pinout, but see some modules use "T1,T2,T3" to connect to the motor, others are "T4,T5,T7", and the Dorman board has no labels.

Yes, that is the motor I refer to as "the new motor".

My board has T1, T2 and T3. T1 is HI speed. T2 is LO speed and T3 is ground.

[ArTrvlr]

It seems to me that replacing a 500k pot with a series of fixed resistances with maximum 680k is probably close enough.

Given the progression of the values it seems they are used to control the charge rate, so with 680k instead of 500k the longest delay will be a little longer.

Thanks, that's one of the things I wasn't sure of. The other is selecting the right components for that circuit. The values and part numbers shown are obvious, but I don't know how to select from other specs. for those parts. For example wattage ratings for the resistors.

[ArTrvlr]

Quote from: bdunham7 on Today at 03:56:01 am

>Quote from: ArTrvlr on Yesterday at 09:08:53 pm

Here is the "Description and Operation" of the wiper/washer system from the GM service manual.

It seems the wash function is being activated so there should be some way to hook it up differently and avoid that.

This could be it. The WASH switch does bypass the 24k resistor in the switch, but the lower voltage through the resistor could still be triggering that timer. I will disconnect the DK GRN wire going to Terminal D on the motor board and see what happens.
Thanks.

[brucehoult]

It seems to me that replacing a 500k pot with a series of fixed resistances with maximum 680k is probably close enough.

Given the progression of the values it seems they are used to control the charge rate, so with 680k instead of 500k the longest delay will be a little longer.

Thanks, that's one of the things I wasn't sure of. The other is selecting the right components for that circuit. The values and part numbers shown are obvious, but I don't know how to select from other specs. for those parts. For example wattage ratings for the resistors.

Small!

With only 12 V available, even the lowest value 35.9k resistor can only have at maximum 0.33 mA pushed through it, or 4 mW.

[m3vuv]

my advice would be scrap the crappy yank tank car and buy european,lets face it 99% of american cars are still dinosoars!, iron cylinder heads, live axles ,side camshafts steeering boxes,3 speed auto single didgit mpg,the list goes on!,do youreself a favor and give it to landfill!.

[Monkeh]

my advice would be scrap the crappy yank tank car and buy european,lets face it 99% of american cars are still dinosoars!, iron cylinder heads, live axles ,side camshafts steeering boxes,3 speed auto single didgit mpg,the list goes on!,do youreself a favor and give it to landfill!.

You're quite a few decades out of date.

He's restoring a vehicle, presumably for the joy of it, not as a daily driver.

[floobydust]

ArTrvlr I was reverse-engineering the GM wiper board but ran out of time. It's hard because of so many models and no decent vehicle wiring diagrams. Maybe later today or tomorrow I can post a schematic.
The Newport wiper motor must have a park switch in it.
GM Wiper boards with 6-pin connectors appear to drive the washer pump, with the one button touch.

Nothing should connect directly to Battery, your schematic shows "B" going there which will give a parasite power drain. It should go to IGN I think. I thought only retractable wipers had the ability to use battery power to park and retract.

[brucehoult]

my advice would be scrap the crappy yank tank car and buy european,lets face it 99% of american cars are still dinosoars!, iron cylinder heads, live axles ,side camshafts steeering boxes,3 speed auto single didgit mpg,the list goes on!,do youreself a favor and give it to landfill!.

You're quite a few decades out of date.

Yeah, back in 2018 I had a trip to the USA and rented a Chevy Malibu and drove is quite extensively in California and Nevada.

I didn't hate it.

The handling was decent, and the 1.6 turbo engine was both more than powerful enough for the car and reasonably economical -- I averaged 34 MPG (6.9 l/100km) on one 590 mile trip.

[Monkeh]

my advice would be scrap the crappy yank tank car and buy european,lets face it 99% of american cars are still dinosoars!, iron cylinder heads, live axles ,side camshafts steeering boxes,3 speed auto single didgit mpg,the list goes on!,do youreself a favor and give it to landfill!.

You're quite a few decades out of date.

Yeah, back in 2018 I had a trip to the USA and rented a Chevy Malibu and drove is quite extensively in California and Nevada.

I didn't hate it.

The handling was decent, and the 1.6 turbo engine was both more than powerful enough for the car and reasonably economical -- I averaged 34 MPG (6.9 l/100km) on one 590 mile trip.

Not great, but better than the Ford (un)Eco(not)Sport I got last time I was over there, which managed a disappointing 24. Thankfully I also rented a Honda Civic which was faster, heavier, larger, and still returned over 40.

[bdunham7]

my advice would be scrap the crappy yank tank car and buy european,lets face it 99% of american cars are still dinosoars!, iron cylinder heads, live axles ,side camshafts steeering boxes,3 speed auto single didgit mpg,the list goes on!,do youreself a favor and give it to landfill!.

You're beyond hilarious.  And you British aren't generally allowed to criticize American cars, otherwise we'll have to start bringing up atrocities like the Triumph Dolomite and Reliant Robin.

That 1958 Oldsmobile AFAIK would have an overhead-valve V8 and a 4-speed Hydramatic automatic transmission.  The same year Rolls-Royce would have come with an F-head (not even all overhead valve) and a standard manual transmission, with an American-made automatic as on option.

But that's all ancient history.  The three-speed iron-headed (nothing wrong with iron heads, b/t/w) pushrod cars all went away 3 decades ago or so.  I've been driving an American-made electric car for almost a decade.

[ArTrvlr]

Quote from: bdunham7 on Today at 03:56:01 am

>Quote from: ArTrvlr on Yesterday at 09:08:53 pm

Here is the "Description and Operation" of the wiper/washer system from the GM service manual.

It seems the wash function is being activated so there should be some way to hook it up differently and avoid that.

This could be it. The WASH switch does bypass the 24k resistor in the switch, but the lower voltage through the resistor could still be triggering that timer. I will disconnect the DK GRN wire going to Terminal D on the motor board and see what happens.
Thanks.

With the board off the motor I disconnected the DK GRN wire that goes to the Mux2 connection shown in the GM diagram. Results: NOTHING in any switch position (including WASH) except HI speed which is a totally different switch circuit directly to the HI speed winding.

So I reconnected that wire and disconnected the GRY wire to the Mux1 connector. Results: MIST, which is a momentary position, momentary LO. DELAY 1, momentary LO, then nothing as I go through the other 4 DELAY positions. Nothing in LO, of course HI works and WASH gave appx. 19 seconds of LO speed.