1991 Camry electrical problem
 

I have a 1991 camry, 4 cyl. automatic, elec door locks & windows, ac. I have had to replace the alternator twice in 4 yrs, this seems excessive to me. The last one had the white insulators burnt inside of it. Now here is what my big question is. Everytime you touch the brakes and the switch makes its contact there is a flash in the headlights. This is also happening when the lights are off but it is easier to see when on. I can see no real MAJOR power drain when I have a volt meter at the battery and hit the brakes. I'm thinking I have a short or something causing the alt. to burn up. Any ideas or suggestions would be awesome.

Concur on a short or other issue causing stress on the alt and premature failure.

Suggest first finding a wiring diagram. Perhaps your local library has service info to copy or pickup a low cost Haynes manual.

The brake wiring is not normally tied into the headlights thus this is place to start. One area where the brake wiring can fail is where it transitions from the chassis to the trunk lid. Make sure the wiring is not damaged in this area from excess flexing.

The brake light system incorporates a light out sensor located on the drivers side wall of the trunk. This sensor can fail and cause back feeding of power into other circuits.

Also check wiring between alt and harness wiring, large diameter wire on alt and 80A alt fuse and the fuse itself for corrosion or damage. The ground wire between engine and chassis, battery cables and battery cable connections including negative connection at chassis.

It may not be a current drain over time but a brief short, something causing a voltage spike, etc.

I second what Joey has said. Quite possibly a ground issue.

I have already checked and cleaned the grounds from battery to chassis and from battery to engine. Are there any more grounds? I will check the other wiring you suggested and let you know. Thanks for the help.

The only other ground for the alt is the alt case itself.