1992 Toyota Paseo

Electrical problem
1992 Toyota Paseo 4 cyl Front Wheel Drive Manual 166000 miles

My battery light (pic of battery) and brake light (the word " brake" ) on my dashboard started coming on. They come on at the same time and go off at the same time. This has been several days. No one will look to see if it's a code. They aded brake fluid and changed the alternator belt. They sprayed some gunk off a wiring harness. ≪ eye roll> If they were separate problems, the ligths would come on independantly. It's still doing it.
Last night, in the dark, I realized that when the dash idiom lights come on ( at the same time, mind you), the headlights get brighter and the fan speeds up. After a while, they go off and everything returns to normal. Could it be the voltage regulator? This all started suddenly when I was driving down the freeway on a sunny day with no traffic. There is no book publishe dfor this car. I'd get rid of it, but it gets 38 mpg.
September 23, 2009.

Tell me how do the brakes feel? I ask because many Toyota's in that vintage have the two lights tied together when it senses a master cylinder problem. Many people don't know this. Let me know about how the brakes feel and if all it good there then I will look over the wiring diagram to see what else might cause them to both come on.

Sep 23, 2009.
The brakes are fantastic. The two lights come on (at the same time) when I am not hitting the brakes. It's random. Not effected by bumps, curves in the road, etc.
I've tried jiggling the parking brake handle, too, no effect.

Sep 23, 2009.
That I understand the two lights are tied together. Meaning that if you a problem with the charging system or the brakes both lights come on it is a Toyota thing. So what I would check is the yellow wire with the blue stipe on the back of the alternator make sure it has a good connection and there is also a brake warning switch on the proportioning valve. The wire going to it should be yellow with a red stripe make sure the connection there is good. It may be that the brake warning switch is bad too or the wire may be touching metal with a bear spot on it an make the light come on. Let me know what you find.

Sep 24, 2009.