Tercel brake/battery light mysteries

I have a 1992 Toyota Tercel with almost 200k on it. The thing runs great, but this past monday when I got in it, the brake and battery light stayed on…so naturally I then drove it 150 miles round trip. The battery died in the grocery store, so I jumped it and brought it home. The battery has some corrosion on it, so I went and bought a new one…battery and brake lights still on, so I checked the alternator, which was fried, shockingly, so I replaced that…you guessed it, the lights are still on. I checked the fuses, they seems fine, so I drove it to work, runs fine, but I can tell the voltage is low by the accessories. The lights stay on, I dont know what to look at next…does this thing have a voltage regulator? Any advice please…HELP!

The voltage regulator and the brushes are located under the back cover of the alternator and are serviceable. However, if the alternator was replaced those components should have also been replaced if was remanufactured instead of rebuilt. Because usually when both the brake light and battery light come on a Toyota of your vintage, it meant the brushes were worn in the alternator.


Huh,that seems reasonable…thanks fro the info. So unless I got a bum alternator, then that is not the reason for the lights?

Oh also of note, the brushes were nearly melted…

Did you buy your alternator from the auto parts store? Those are notoriously unreliable, even right out of the box. I would try a junk yard alternator for a '92. Either that or bite the bullet and pay the big bucks to the dealer for an OEM part.

This alternator didn’t loose its ground did it? Just my WAG

Have you checked for continuity between the battery and the alternator? There might be a fusible link in the wiring.

My multimeter leads won’t reach that far. Just take it to a shop for troubleshooting. Somewhere a short is burning up the alternator. It could be from the wire that goes between the battery and alternator shorting somewhere…like against the body of the alternator. It could be elsewhere. The time and money you will spend changing parts could be saved by a good mechanic doing the troubleshooting and finding, and fixing, the fault. YOU could do IF you could follow the power distribution and check the circuits with a multimeter.

I did buy it from a parts store, it wasnt cheap either…all the fuses seem fine, all the wires seem fine. I am going to clean the connections on some of the wires and then I guess take it somewhere, still runs great though LOL!

In some years for the Tercel, there were two alternators available, and they are not interchangeable. But I think if you have the wrong one, you can’t wire it up, the wiring harnesses were different, and in some years, some of the alternators had external regulators, but I think those were in the 80’s, not in the 90’s.

My guess is that the reman you got has a defective diode in it. When the brake and battery lights come on together, it means the alternator is not putting out.

Buddy of mine had a similar issue on a 94…turns out the negative battery wire was exposed, he drove it for a year without that thing that holds the battery in place and this caused the battery to move around and pull on the wires…it was hard to detect because the tear was underneath and towards the firewall…any hoot…always check the battery terminals & wires