What happens if you connect jumper cables incorrectly?

[Bav///Man]

A couple of my genius friends did this today. The car was dead and they jumped it wrong (switched the positive and negative cables on the dead car) and it sparked. Now nothing will turn on in the car at all except for the headlights. Is there a chance that they blew something big? I was told and have read that if you jump incorrectly the worst thing that happens is the battery gets fried. True? Thanks.

P.S. - It wasn't my car.

[Nics]

I think the worst that could happen is you blow your ECU. I dunno for shure though..

[Nick MD]

Originally posted by Bav///Man
A couple of my genious friends did this today.

Do your "genious" friends at least know how to spell genius? :stickoutt

Probably all they did was kill the battery... but they might have fried some other circuitry as well. Try replacing the battery and see if it works.

[PortalBMW]

Originally posted by nickdtm


Do your "genious" friends at least know how to spell genius? :stickoutt

Probably all they did was kill the battery... but they might have fried some other circuitry as well. Try replacing the battery and see if it works.

Do you have a solar panel on your car? Im just wondering how your headlights are turning on?:dunno

[Bav///Man]

Originally posted by nickdtm


Do your "genious" friends at least know how to spell genius? :stickoutt


Actually no, they don't. They also don't know how to spell "automatic" or "groceries." :stickoutt Where was genius spelled wrong in my post, anyways? ;)

Thanks for the reply, though. Seriously, I hope that it is the battery, but if it's not, what would be the most $$ that it would take to fix the car? I know you don't know much about what's wrong, just as I don't, but guestimates? BTW, it's a '95 Mazda Protege.


Originally posted by PortalBMW


Do you have a solar panel on your car? Im just wondering how your headlights are turning on?:dunno

Same here. Craziness.

[jesd325is]

dead battery would mean very dim headlights. a majority of the cars electronics are not sensitive to polarity,mainly motors are, and everything mostly needs a switch to run it anyways, but check the battery for damage or any voltage as well.
but one of my friends right here says you would ruin all of your electrical system, and your ecu

[Bry]

Originally posted by Bav///Man


Actually no, they don't. They also don't know how to spell "automatic" or "groceries." :stickoutt Where was genius spelled wrong in my post, anyways? ;)

Thanks for the reply, though. Seriously, I hope that it is the battery, but if it's not, what would be the most $$ that it would take to fix the car? I know you don't know much about what's wrong, just as I don't, but guestimates? BTW, it's a '95 Mazda Protege.



Same here. Craziness.

You cheater! You edited your post, and spelled genius the correct way! :stickoutt

[Bav///Man]

Originally posted by Bry


You cheater! You edited your post, and spelled genius the correct way! :stickoutt

haha...that wasn't me http://mywebpages.comcast.net/fick48/Dave/paranoid.gif

[iwannadinanm3]

since we're on the topic, what happens if u connect the neg and pos cable of those little jumpers that u can jump ur car without another car, like the little battery pack ones, get what im sayin?

[98323iConv]

My dad did this once trying to jump his old 81' toyota with my moms 94' lexus. The toyota was fine, but the lexus wouldn't work at all. It had to be towed in and in the end, the internal computer was fried or somethin...not sure exactly but i remeber it cost alot to fix.

[XOC]

Geez, why don't they just have a big diode or something before the ECU so it can't get fried that way.

[Streamline]

Just like what the other guys have said. You could have fried your ecu. HOWEVER, it is also possible that you actually may have burnt out a Main Fuse. (This is true for the Nissans and Mazdas that I've worked on...so this MAY be applicable to BMWs as well).

This Main Fuse is there to prevent situations exactly like this (crossing jumper cables, etc.). It is a preventitive measure used to protect your ecu. Usually, the Main Fuse controls the major electronics of your car, like the dashboard, interior lights, door lights, etc. After you replace that, you should see the electronics working again.

Now, I'm not talking about the regular sized fuses. I'm talking about a LARGE sized fuse. Contact your local BMW dealer to see if they can identify what I'm talking about.

Usually, these LARGE fuses are in a fuse box located in the engine compartment (not too far from the Battery). Also, there is probably a battery cable which runs near or directly to this fuse box.

See if this helps. Good luck.