hi, the other day my father installed my battery in backwards.... now the car won't start, as nothing happens when you turn the key... does anyone know which fuse or relay might have broken..??

thanks harry

What sort of car/motor??

 

Electronic ignition??

ke 55 carolla not electronic distributor..

like when you turn the key to accesoriece or on position no light or anything come on.?

Id be checking all the fuses, there arent that many of them.

 

can't recall if there is a fusable link up near the battery, but check that too if its got one.

Yeah checked them all well all the see able ones.. Is there any ignition fuses ?

Is the battery still OK? Have you tried it in another car or can you get headlights & horn OK?

 

What did you do with the battery in backwards, and what happened?? Sparks?? Smoke? Crank it over?

 

I can't think of anything that would blow up from just having it in backwards. before you turn it on the only thing hat uses power would be the clock.

 

If you turned the ignition on it might do funny things to the voltage regulator, but even that is mainly mechanical and it wouldn't worry diodes. The starter motor might freak, or the coil, but cars were positive earth until the 1950s without problems.

I did this once in my ae92 Sx. Fried lots of fuses. I would be checking them all there aren't many in the early girls.

Yeah there was smoke but mainly from the speaker/head unit wires which I have tested and they have power all the way to the head unit, the lights and horn work

But nothing to do with the ignition work/immobilizer ect all don't work ?

Fuse in immobilizer is good

Do you think the immobiliser is fried? That will have electronics in it.

 

Can you bypass it? I assume it was added recently, as in the last 10years. You might not have had any more current flowing than usual so the fuse wouldn't blow, but the direction of current might upset some transistors.

Might have fried the alternator too.

could be possible,

does any one now how to bypass the immobiliser do i just cut and hook it back up the original ?

WHY WOULD YOU EVER INSTALL AN IMMOBILISER!

 

But seriously, I'd start by checking the ignition barrel for power with a multimeter/test light, and if you're not getting power there, the only thing that should fail before that is the fusible links. Everything in the car (except for the headlights and main power to starter motor [power to starter solenoid comes through fusible links]) draws power through the fusible links.

Eg. If you go to the back of the ignition barrel and hold a test light/mutlimeter on the terminal marked ACC, and then you turn the key to ACC and you don't get a reading, the fusible link up near the positive on the battery has failed.

And you should just be able to follow that process the whole way through the wiring until you find the problem. Here's the engine section of a KE diagram to help you:

 

WHY WOULD YOU EVER INSTALL AN IMMOBILISER!

 

To stop junkies from taking your car for a joyride & burning it when they're done, one has prevented my car from suffering that fate twice now. I do see the added complications that one would add to wiring, especially if installed prior to your ownership of the car. :)