1996 M3 Electrical System Issues

[Cokewell]

Things that have happened

1. I'm driving home one night, my Escort 8500 X50 reads a dropping voltage. Lights start dimming, ABS light comes on, Airbag light comes on, ASC light comes on, Chimes start ringing. I pull over and turn car off. Car will not restart.

2. I get a jump from some random, car runs about five miles down the road. I get another jump which gets me home.

3. I pull the battery out of my dad's 330 and put that in the next morning to get to work. System reads steady voltage during the drive (lower than normal 14.4 but still steady). After work car is totally dead and will not start

4. I Have it towed home, remove the battery and charge it, and swap in a new Alternator three days ago. I am unable to monitor system voltage because I sold my 8500 X50 to finance the new alternator.

5. Car starts fine this morning (after a long night of ass kicking driving with JCapelo & J_dEAl), I drive to Sound Advice and chill for a bit and car starts fine again.

6. I'm on hillsborough and those lights and chimes start going off so I pull over. I get a jump, make it to Autozone, and have them charge and test my battery. The battery is good. I put the battery in the car, start it, and have them hook up the machine to it. System voltage stays steady as car sits there running. (12.7-12.8).

7. I drive home and the lights start turning on again as I get back into my neighborhood. I turn the car off in the garage, and big surprise ... it wont start again.


Now what the hell is going on here. It's not the Alternator and it's not the battery. I have a feeling this is going to be a HUGE pain in the ass. Any and all assistance is appreciated, Mechanic is my last resort.


:thanks:

[DeadSailor]

i not too savee with this stuff but this sort of thing happend to my moms car. went through 2 batteries and it ended up being some cable that was touched something weird...so it wasnt grounded right. even though the alt was working fine it couldnt charge the battey

[Cokewell]

Yeah man, that's what I'm thinking. Faulty wiring somewhere but I hope that's not the case. I'm checking it all out with a digital multimeter tomorrow at work to see if there are any circuits drawing a lot of current constantly.

[kelso]

gotta be wiring, something is drawing all your juice.

[Cokewell]

It's gonna be a bitch trying to find what and where. I hate wiring.

[kelso]

yea wiring is the devil in situations like this... weird though youve had the car how long and it never did this before? did you do any stereo work recently? or any work at all that could have knocked some wires around and touched

[silver-e34]

check your ground wires from the battery and the wire coming from the alt to the battery make sure the contacts are all clean more than likely thats your problem

[LDadrenaline]

my dad's suburban seems to have similar electrical issues and its not the battery or alternator either.... the dealership wouldnt do any work because the cai he put on (got it for better gas mileage) apparently caused the electrical issues....yeah right..... But I agree that its probably something with the wiring and the bad grounding seems like the most reasonable thing

[944attack]

also check for corroded wires, many times those thick battery wired that run from the terminals turn green/dark brown, and wont conduct the elctrical currents properly. You can splice into the side of a wire to check the metal color, and if it's good it should still be a shiny copper or sometimes silver color.

[Cokewell]

I'm going to remove the new alternator and have it tested ... Popular opinion is that the alt was bad out of the box. Aparrantly many people have seen this type of thing before.

[silver-e34]

you dont have to take it out just get voltage meter and check voltage at the battery it should be above 13.5v but no higher than 15v with the engine running anything other than that its defective

[kelso]

yea defective parts happen all the time, still a weird issue

[TheDarkSide]

you dont have to take it out just get voltage meter and check voltage at the battery it should be above 13.5v but no higher than 15v with the engine running anything other than that its defective

:ditto: Unless it is already out...

[Cokewell]

It's already out, just waiting for the new one to get to Motometrics.

[Cokewell]

Sawheet. Thanks to Motometrics, I got it in. System voltage reads 12.5-12.7 when car is off ... 14.1-14.3 when car is running.

Hopefully this bitch lasts more than a day. Has anyone ever heard of a break-in period for alternators? I'm going to do an amp draw test tomorrow at work to see if there is something that might have killed the preceding alts.

Anyway. Just happy she's running again.

[TheDarkSide]

that's good news Mitch!

[944attack]

I got a used alternator from a junkyard that didnt work for the first two days, but then all of a sudden jumped to life and has worked fine for the last year.

[Cokewell]

Weird. I've been watching my voltage like a hawk. I'm all paranoid about it now.