Put the Battery in the Wrong way

JoeySully

Uh oh

Friend of mine put the battery into his yaris this moring the wrong way round ie + to - and visa versa. turned on ignition nada happened except headlight light on the dash lit up but no other lights at all. Then put it the correct way round. turned ignition no lights no soud, nothing. whats gone wrong?
battery was full cause it came outa my car and it had started mine already.

Blown fuse, ECU trouble? i think its a 2003 model

Mr.Diagnostic

I dont see many Toyota's and I am at home so dont have access to any tech info but here goes -

Most Toyotas have large main fuses that will blow in a case like that. I think they will be located beside the battery pos terminal, they were on the older one's. Check that first. Then check all the smaller fuses. If that is all ok then it is likely you have done further damage.

Henry Ford III

That little error could have absolutely fried the electrics.

I hope it's only a fuse that's blown.

gyppo

Sorry to hear about your friends car - as others have said, hopefully the mainfuse blew, but if any dash lights came on, it meant that the fuse had'nt blown at that stage.
Any smoke or signs/smells of burning? The diodes in the rectifier pack of the alternator could have taken a hit. Thats what happened to a friends car when he did the same.
I often wondered why car manufacturers and battery manufacturers never made a keyed system, so that this type of thing could'nt happen.

Dades

I did the same thing on my classic ('72) one night.

Smoke came out of some wiring, and nothing worked at all. After a sleepless night, I tried again the next morning and everything was fine. No probs since.

Moral is: don't panic - it's probably going to work out fine.

colm_mcm

There's a fuse that costs about 35 quid off the positive terminal on the battery. most likely what's gone. (most dealers will be shut this weekend though.)

crosstownk

It's quite possible that the main fuse didn't blow as the current required to damage any components is much less than that required to blow the main fuse. Your mate must have tried real hard to get things wrong as the positive and negative terminals are different sizes. Did the donor battery come from a Toyota? There are different types of batteries, with different configurations for fitting - batteries aren't universal. It sounds to me like the batteries were from different cars. There is a good chance that the electronics have been fried.

With any luck the main fuse may have blown, and as colm says, €35 for a new fuse should sort it out. If it doesn't then it could be a costly error.

colm_mcm

some toyotas (even the same models) have the positive terminals on different sides of the batteries. easy enough mistake to make. If the ECU was fried and the main fuse intact, other components like the horn and headlihts would still be working.

crosstownk

colm_mcm wrote:

some toyotas (even the same models) have the positive terminals on different sides of the batteries. easy enough mistake to make. If the ECU was fried and the main fuse intact, other components like the horn and headlihts would still be working.

Very true. So hopefully, for the OP, it's the main fuse!

JoeySully

Thanks for the responses, main fuse was the problem. sorted

DublinDilbert

Nearly All ECUs now are reverse battery protected, so will not be affected at all by connecting the battery the wrong way.

There is a second method used to protect ECUs ( typically used for high current ECUs ), which involves protecting the ECU, by blowing the fuse feeding it. This is achieved by placing a reversed biased diode across the ECU supply lines, hence if the ECU is connected in reverse this diode will start to conduct, hence blowing the fuse.

Most cars now have centralised load dump protection at, or near, the alternator, which is typically a large zener diode, which will if connected in reverse bias blow the main fuse....

glad you got it sorted...