What could have been damaged by connecting battery backwards?

Question

I went to replace the battery on a 1999 Taurus SE I have recently been working on. Previously the car would not start, but replaced the alternator, cleaned terminals, and borrowed a good battery, which made it start right up. It ran fine and when i purchased my own battery for the car, I made a VERY stupid mistake by hooking it up to the wrong terminals. I did not fully connect it, only connected the ground, to the positive by mistake, then when i touched the positive terminal to the negative node on the battery the horn honked, trunk popped open, and some sparks shot off the battery. I immediately realized what was wrong and reconnected the battery the correct way. However, after several attempts, the farthest i got was getting it running for about a minute until it lost battery power and stalled. I then took the alternator, which I just replaced, to auto-zone to get tested, where they told me it was fried. Could other parts have been damaged or will it run fine if i just replace the alternator?

Answer 1

first connecting a battery backwards shouldn't fry a good alternator as there is a fuse that is supposed to protect that however you said you got the alternator from auto zone :( i cant install them as the failure rate is to high my warranty is 1 year on all my work and it costs my to much if i warranty to often

as far as other parts they are protected with diodes you should be ok

Answer 2

Yes, other parts could be damaged. It's a good sign that you did have it running for even a little while. Go ahead and replace the alternator (warranty exchange! :-D). Sounds to me like the diodes on the alternator were probably fried. I predict it will run much better after that. Just turn the car on and make sure all your systems are working (interior and exterior lights, radio, horn, also warning lights on the dash). If anything is not working first check the fuses.

The worst thing that can happen is you can fry the computer, but because the car was running at all means the computer is probably fine. A fried computer is usually an all or nothing kind of thing.

***EDIT***: Yes! If a battery terminal is cracked this WILL cause problems ESPECIALLY if the battery is bad. You lose ignition voltage, lose your spark and the engine runs like poo.

I just fixed someones Mustang about a month ago. The engine was running horribly. They took it to a shop and the shop quoted them $1100 for the repair but the person didnt trust the shop so they called me. It had a bad battery and cracked terminal end. I replaced them and it runs like a top.

FIX THE TERMINAL END :-D

Answer 3

All the other answers look pretty good to me. But I think it's also possible that the car will have to run in reverse forever. Are the rear view mirrors still working? You may need them.

Thanks for the laugh. I'm sorry this happened to you but your story made my day, Remember, FORD spelled backwards is DROF.

Answer 4

Just replace the alternator for now, you might just be lucky, if however you have damaged the wiring loom, that is a biggy and could be expensive, although if the motor ran for a while, you might have got away with it.

Answer 5

by incorrectly connecting the battery you could have set off all your airbags and there is a good possibility that you have also fried the ecm and the bcm the ecm controls the engine and the bcm controls all your door lock alarms radio codes ect.

good luck

Answer 6

chances are you did not dammage any thing. recharge the battery. and connect it right this time. good luck.

Answer 7

yes by doing this you fry ed the brain, too, i look at the fuzes to see if they good