Jim Grant's Tech Tips
89 Toyota Supra Turbo, No Electrical Power
Q: I have an '89 Toyota Supra turbo that has lost all electric power. The battery is fully charged yet there is no electric power being distributed to the car. It appears that everything except the front headlights is dead. You turn the ignition and nothing happens. It is as if there was no battery in the car. I did check some of the fuses and circuit breakers and found nothing blown although I could have missed something. The fact that nothing works leads me to believe there may be one primary distribution point or fuse /circuit breaker for power which hopefully is where the problem lies. Can you help with this or give me some idea where to start trouble shooting? One last thing that might help. The battery was weak and my son tried to jump start the car. He could not get it started and I am somewhat suspicious that he may have connected the positive terminal to the negative terminal when he was trying to jump-start the car. He swears he did not but it’s a possibility. If this were the case, can you tell me what may have been damaged or once again where to concentrate my trouble shooting?
The devil is in the details and that last piece of information you provided is very useful. You need to look closely at the #2 fuse/relay panel. In the middle of that fuse panel are 2 fuses marked AM2 which is a 30 amp fuse and AM1 which is a 40 amp fuse. These 2 fuses just happen to be responsible for the electrical power that goes to the ignition switch and out to just about everything else other than the headlights. If you find that those 2 fuses have failed that is a good thing. After you replace them and have the Turbo spinning again in your Supra take a little time to work with your son on boosting batteries.