the bad jump -- reverse polarity

[BimmerBobby]

OK, I have to get something off my chest.

I jump-started my e30 with the polarity reversed. I did not realize my error until after I had attempted to start the car.
Yeah, ok, I am stupider than your retarded nephews, yes, I know, I've already been living with this for about a week now, and I hate myself more than ever. ANyone who wants to join the pigpile, feel free to post-\/\/hore.


How deep does this go? I need to isolate the problem.

Let me explain what I've already fixed.
At first:
-Car would run fine, until jumper cables from borrowed car were removed.
-the fuse in the trunk *seems* unaffected (not transparent)
-If battery was left connected, would be fully drained within 3 minutes.
-The dashboard battery light was on, even when no key in the ignition.
so I:
-Re-charged/tested battery, which seems to be fine
-I *do* have a healthy spare battery as well
-REPLACED ALTERNATOR on Sunday with top-grade reman. part (no shortcuts)

... the car started and ran on its own power until I shut it off.
I restarted it several times, and left the battery (original) connected overnight.
The only oddball behavior I noticed: the ABS light on the dash is on.
Today, the car started, and restarted 5 times today. Until I drove to see my folks across town.

The car will not start, but all accessories operate: windows, radio, etc etc.
The battery light is not illuminated.

1) could my "bad jump" have ruined the starter motor? Is it possible for the starter to work sometimes, and not other times?

2) Would I know by now if the ECU is fried? The car started and ran 10 times over the last 36 hours.

3) what is the next step?


Please, anyone who's been through this with an e30, or can give a positive contribution, I'd really appreciate your thoughts before I waste time on "troubleshooting" whims and/or buying parts I don't need.

[evil_twin]

Fusible link perhaps.

[BimmerBobby]

Fusible link perhaps.

1) is that the one in the trunk, under the carpet, that follows the positive cable?
2) is a bad fusible link something that would allow my car to start 10 times, then poop out all of a sudden?
3) what symptoms indicate that this could be the cause?

... just trying to understand.

[gaineyz]

1) is that the one in the trunk, under the carpet, that follows the positive cable?
2) is a bad fusible link something that would allow my car to start 10 times, then poop out all of a sudden?
3) what symptoms indicate that this could be the cause?

... just trying to understand.

BimmerBobby - I'm sure you are long gone from these forums, but in the off-chance that you are still here... My son just did the same darn thing to my car. It's having similar symptoms to those you describe. Can you tell me what the end result was of your efforts? what was broken and what did you have to replace?

Thanks.

[earthwormjim]

BimmerBobby - I'm sure you are long gone from these forums, but in the off-chance that you are still here... My son just did the same darn thing to my car. It's having similar symptoms to those you describe. Can you tell me what the end result was of your efforts? what was broken and what did you have to replace?

Thanks.

Check all fuses in the engine bay, most of the car's electronics are reverse polarity protected with bypass diodes, meaning they probably just opened some fuses.

If jumpered at the engine bay side, good chance the alternator's diodes are dead. If at the battery end, it's possible the fusable link is open, or partially open.

It's been my experience that the alternator usually sacrifices itself before other components if we're talking just a short period of time. For longer periods of time, that gets into the battery damage and/or fire realm.