I am having problems finding the reason why my brake warning light is on. This is for a 92 S10 Pickup, no ABS. I know this is an F-Body forum, but I have gotten no help elsewhere and this place has been my best source of info! And, not having this fixed is racking miles on my 89 GTA!

I replaced :
rear brake hardware, rear wheel cylinders, rear brake hose, and master cylinder. I also bled the brakes countless times.

I don't lose brake fluid, and braking seems fine. I can hear/see the brakes engage while bleeding. I also don't believe it's just a bad e-brake switch. After resetting, brake light doesn't really come on when I hit the brake. After the rear brake job, it was off for a while and came on while cruising, now its always on.

Before I change the combination valve (once I find one!) and/or calipers, any other suggestions?

 

There's a clue in there somewhere....

The hydraulic switch works off of the pressure differential created by a hydraulic failure in one "end" of the brakes or the other; e.g. if the rears fail, the difference in pressure between the fronts and the rears will operate the switch.

Note that PRESSURE IS REQUIRED; meaning, the ONLY time that it is POSSIBLE for the hydraulic switch to be operated, is while braking.

So: is this the hydraulic switch, correctly operating and indicating a genuine (real) service brake problem?

I don't think so.

Unplug the wire from the switch on the parking brake (that's all these cars have besides the service brakes, they don't have an "emergency brake" whatever that might consist of); and see if the light goes out.

If it goes out, then the problem is the parking brake switch.

Or, unplug the wire from the combo valve, and see if the light goes out. If it does, then the switch in the combo valve is probably bad; if it doesn't, then the problem is the parking brake circuit.

Note also, if you have the electric hatch release, that's tied into the parking brake circuit too (since the parking brake has to be operated for the hatch to be opened while the engine is running); but try the simple stuff first.

 

Thanks for the advice - although I am a bit puzzled now.

I disconnected the parking brake sensor - light still on. In fact - light got a little dimmer with this disconnected.
I disconnected the combo valve sensor - light still on.

I unplugged this flat, rectangular box, probably a computer, that is next to the combo valve - waited a few seconds, then plugged it back in. When I restarted the truck, the light was out this time, but after about 5 seconds it came back on! (note: I don't have abs and no computer codes are present)

Could something else be triggering this light? Even the GM manual is no help here.

thanks for any more advice.

 

Evidently....

I don't think there's any kind of computer associated with the brakes. I have no clue what kind of a box you might be talking about, maybe a pic would help.

However, if your car has the electric hatch release, then as mentioned, something about that circuit could be causing it.

 

I feel stupid for not realizing this before... I actually have rear abs and that box is a computer for the abs. I had just assumed that to have abs you have a dash abs light, but this is not the case for older vehicles. So once I read how to retrieve the code by jumping a different contact in the aldl, I have something to go on now.

Oh, and a pickup truck doesn't have a rear hatch.

 

Oh so this post doesn't even belong here.... it's not about a 3rd gen Camaro or Firebird at all. Sorry.

Guess I should have paid more attention.