TheTank

Ok over the past month, every once in a while (like maybe every 3 times I turn my truck on to drive it) the Brake! light stays lit on the dash for about 3 minutes and then shuts off and doesn't come back on. But tonight I was driving it home and it was on the whole 20 minute drive home, fading in and out. It was just faintly there, and it was kind of getting brighter and darker. Anyone know what could be wrong that would cause the light to come on?? The brake fluid reservoir is full and the sensor seems to be clipped in all the way. Brakes work fine.....Any ideas??

ATLRoach

wear sensor or the fluid sensor is going bad?

Rick F.

The brake light in my '90 used to come on anytime the fluid was the slightest bit below the fill line. The same was true with a co-worker that had a '90 p/u.

TheTank

Yeah the fluid was about halfway between low and full so I filled it up, but it's back on. Now it doesn't even light up all the way though, just very dim. But wear sensor? What is that and where's it located? I didn't think there was one.

dusty98

I've seen that twice on my 90. Once when the sensor in the brake fluid cap went out. The other was when the alternator started dying.
The brake sensor going didn't seem to have any effect, except the annoying light. The alternator was a different story

TheTank

Ok there has to be something going wrong with the whole system since the light is obviously coming on, which I think I can find by replacing the fluid sensor or whatever, but my concern now is the fact that the light isn't coming on all the way. It was dimming in and out the whole way home tonight. Could the bulb be going out? I highly doubt this, but it's really getting annoying.

TheTank

Yup I went through the alternator thing a couple months ago. It went bad REAL quick. One afternoon it won't start after school, and magically starts after a while. Then I'm driving to Toyota to get a new battery that night hoping that will fix it and it dies about every 100 yards. That wasn't fun, but I think the alternator is going bad again because it doesn't keep up charge when I'm just like sitting at lights, and when I have the blinkers on the battery gauge shows the voltage dropping to the lowest line every time the blinkers blink. I'm thinking a high output one is going in soon.

TheTank

What high output unit did you go with and is it holding up well? Does the gauge drop dramatically with the blinkers on?

Pretacopower

I had a very similar problem where my brake light would come on whenever I accelerated or drove on a hill. Turns out my brake fluid was low. If it's not RIGHT on the full line, it may trigger the sensor. Mine looked full to me, but after adding only a spoonful, the light went away.