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Cant start car after hooking Battery Up Backwards

Discussion in 'Warranty questions' started by Bimmerdude3, Dec 6, 2010.

    Bimmerdude3 guest

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    Last night I was working on the car and got everything back together to get her moving again. It was late and for some reason the colors on my battery are backwards, red and black are switched. So not paying attention I hooked the positive to the negative and negative to the positve.

    I was wondering why there were sparks, lol. Anyway I did this on my sport bike before and it popped out a breaker switch or relay I forgot what its called. But instead of blowing fuses it deactivates the electrical system to prevent harm.

    Is there something like that on the e30?? If not how do I start my car?

    BTW car wont get any power now at all. So chances are someting is probably fried. Im going to check the fuses.
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    John in VA

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    You could have fried the ECU. Do have a spare or someone nearby with a known good one you can try?
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    This thread may help you troubleshoot your issues - But there are a few main ideas I can bullet point for you:

    * Check all Fuses and record any that are blown before replacing them. Then re - engage battery power. Did any blow immediately? (Fried Module likely)

    * DME may be cooked. Have a spare to try (as previously suggested)

    *Is there an inline fuse in your battery cable? Perhaps hidden?

    bon chance

    Bimmerdude3 guest

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    Thanks for the quick responses guys.

    Dont have one on me this is my first e30, im coming from the e36 world. I was thinking of doing the 327i stroker swap I could pick up another ETA ecu as well the parts are cheap enough. Thatll be my last course of action though.

    I will check the fuses not sure how to check the box like ones but I think e36s use some similar fuses, I have like 20 lbs in baggies of fuses from like 12 cars lol. Ill try swapping them out. I'll do the fuses right now.

    DME getting cooked is proabbly most likely because thats the way my luck turns lol

    And im not sure about an inline fuse, that would have to be aftermarket right? I believe the PO said he relocated the battery to the trunk, not sure about this. If he did it would be pretty stupid to bury a fuse deep under a bunch of carpeting id think so lets hope thats not the case but ill check around for one in a minute after doing the fuses
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    ECU's seem to be readily for sale via Ebay if you need one, make sure you get the same as what you have (there's a sticker with the numbers on the cover).

    I think the '84 318i and convertibles had/have the battery in the front, most E30's will have the battery in the trunk. I don't know about an inline fuse, but the battery cabling in the trunk is easily examined, up to the firewall. On the other side, you have to pop the rear seat bottom out. I don't think you have to pull the seatback for access to the cable. Good luck sorting it out, hopefully the damage is restricted to fuses &/or the ecu!

    Bimmerdude3 guest

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    Great news, it must have surged the battery or something like that. I yanked the battery out of my M3 and dropped it in (the correct way this time) and its cranking. Wont turn over, she hasnt been started in like 3 months really though so im not surprised.

    Got another front fire which blew the rubber boot and airbox off and left the rubber elbow in flames hahaha. I think the problem might be that i didnt tighten anything down. Ill report if she starts or not.
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    Just some FYI regarding ECU's.

    The E36 shared some engines with the Z3 and E34 and E39 cars. Just to give you some additional options for parts interchange. Hope everything is ok.

    Bimmerdude3 guest

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    Yeah, I was thinking of swapping in an M50tu/getrag but im way to lazy. Got a perfectly good one, I was almost invloved in one fo those insurance scams rolling into last winter. Got rammed from behind in my "is" while at a stop in traffic on the highway, pushed my car 4 and a half car lengths till about 10 inches away from the car in front of me, next 3 cars infront of me were all about an inch from each other and the guy in the front happened to be in cahoots with the guy who rammed me aka his driver (he stated this). Anyway long story short I stripped the car down so im sitting on a perfectly good m50 that needs a home.

    If the requirments for join CCA as a club racer aren't to tough for me (on the cash front mostly) hopefully I can slap together a spec racer over the winter.

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