Accidentally reversed polarity while jumping

[LowFourteen95]

I tried to jump start my car off of my roommates, BMW tonight. It was dark out and snowing, so I was trying to be quick about it. Her battery for some reason has a pink wire for the ground and a black wire for the positive, so naturally I latched on to the wrong terminals on her car. So I hooked it up and jumped into my car (1997 Talon) only to smell dreaded burnt electrical stink. Also, the wipers were going and the cruise control light was lit up on the instrument cluster. The wipers wouldn't turn off with the lever either. I'm really hoping it was just fuses that went out somehow. Is it possible the ECU is toast? The engine would turn over at a normal speed once I corrected the jumper cables, but it wouldn't fire. I'm really up a creek if it is the ECU since I have DSM link and so would need a socketed 95 to replace it. The city will also tow it on me since it is currently parked on the wrong side of the street due to winter snow removal side swithing rules. If anybody else has had this problem, I'd appreciate help.

 

[BISHILVR]

actually you'll be lucky if it's ONLY the ecu, other things that could be toast would be radio, cruise control module, keyless entry module, ignition module, cas, etc. but i would say that theres a 90% chance you at least cooked the ecu, check for blown fuses first though.

 

[LowFourteen95]

You know, what's strange though is that her car is just fine. I mean, doesn't this sort of thing happen quite frequently? Granted, I know positive goes to positve and negative to negative, but when its dark and snowy, with wront colored wires, things can happen. Just seems like mitu should have built in safety.

 

[BISHILVR]

well, there is a certain level of safety built in, but it is only for small voltage spikes from the alternator or static, relays operating normally, electric motors operating normally, but you introduced hundreds of amps to the system, and there just is'nt any real way to protect sensitive electronics that normally only see millivolts when somone adds hundreds of amps in the wrong polarity. it's not just cars though, the same thing happens to bikes, quads, lawnmowers, etc. they just don't plan on someone connecting a battery backwards. the only reason i can think of for her car not being damaged is that her polarity was'nt reversed like yours, plus her engine was probably running and the alternator was putting out alot of amperage to overcome that momentary short that you created when you reverse biased your system. i would have to think that you took a couple of years off of her system though.

 

[Defiant]

Just seems like mitu should have built in safety.

They did. They didn't include jumper cables. You defeated their safeguard.

 

[LowFourteen95]

Okay, I have an update. First I replaced the alternator fusible link (100 A) which was blown. Then I tried to jump the car again and it would just turn over, but make no attempt to fire up. Then I put in the new ecu that I rounded up and tried it again. The dash lights still go through their diagnostic check like normal and relays are clicking, but the engine won't even attempt to turn over.

To summarize: Bad ecu = engine will turn over but not start

Good ecu = engine will not turn over

 

[AiR]

check your ignition fusable link etc... thats in the fuse box under the hood

 

[LowFourteen95]

Another update:

Changed nothing, just waited about a half hour and went back out. Then it was able to turn over and start. Guess it was just posessed. So anyway now, the next thing I want to sort out is to get the radio working again. It's all factory infinity audio system. I replaced the 15 amp fuse for the amp, which is in the litter fuse cluster under the drivers side dash. It looks like there is a 10 amp fuse for the radio in this little funky yellow fuse holder under the hood. It's with the other fuses, but for some reason they are contained in this yellow do-hickey which I can't figure out how to remove. Do I have to get a channel-lock pliars on it and just pull?

 

[Defiant]

It looks like there is a 10 amp fuse for the radio in this little funky yellow fuse holder under the hood. It's with the other fuses, but for some reason they are contained in this yellow do-hickey which I can't figure out how to remove.

Those are fusible links. You'll find matches for them in the rack at AutoKragenGrandZonePepSchucksBoys. They plug in like fuses.

 

[44pirate]

Any updates?