Electronics > Repair
Need help diagnosing a no crank no start issue on a 2000 323 E46 BMW
poot36:
I have been helping my dad attempt to fix this issue and we think it may be a EWS issue but we are not sure. My dad has posted on these two forums but has not really got any good advice: https://www.e46fanatics.com/threads/intermittent-no-crank-no-start.1329824/ and https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/283008-no-crank-no-start-issue-need-help
Not really sure where to take it from here. Any advice would be welcome.
m k:
Connection problem and a car is not very nice combination.
If problem is a regular connector its measuring can change the situation for quite a long period.
Means that if probing is difficult its practicalities can lead to false good connection.
CAN error and error between controller boxes indicate that it is not a simple switch thing somewhere.
One possibility is a loose connection that leads to a lower voltage and therefore uncertain operation.
RFID is a good candidate for being affected by those kind of things.
Dropped voltage is not necessary very straight forward thing.
I had a Citroen once that had a lifted fuse, by me, for electrical cabin heater.
That fuse didn't burn, but had to be replaced every now and then since its plastic case was melting.
Other Citroen had ashtray light as a headlight height motor fuse, maybe BMW is not that sneaky.
DavidAlfa:
Normally the starter is directly engadged by the key, then the ECU Will enanle injection or not, but should crank.
Maybe BMW is different so do take it too serious.
I'd check the wiring schematics and trace it out.
In most cars there's a hierarchical power distribution, one big beefy relay powers several other and so on, it's not that hard unless it's modern crap full of control units and magic boxes.
If you randomly have 12V at the starter, trace follow tha wire out, at some point you should find something.
Fuse boxes fail on some cars, the internal connections burn, break or whatever, so don't trust only the fuses.
Having said that, I've checked BMW WDS and it's the worst utter piece of crap I've ever seen, no way to track a signal without becoming crazy.
coromonadalix:
some cars now with an transponder
the motor will crank, no fuel pump until the transponder acknowledge the key / security, to test just put aluminum foil to cover completly the keyfob ... unless you have in the key itself a small electronic part
for sure if @op is able to get some electrical schematics ... he could follow the acc line etc ... you have better cars forums then here ...
a random 12v could be some relay / contacts, fuse box intermittance, corroded wires, pinched wires in the harness ... ground issues
good luck
CapLeaker:
I think you either got water and corrosion in a connector or EWL, wiring, fuse box or a simple key issue. Does it have any codes? Weird to have like 6 keys registered to the car. Does the car complain about the key? Hard to tell without seeing what happens on the cluster.
I had the same problem with a 2002 VW back in 04. The problem was that my key wore out, but I could see a key symbol blinking in the dash.
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