91 chev caprice 'dash brake light'

[columnshift]

1991 chevy caprice 305 tbi

The dash warning light for 'brake' suddenly came on about a week ago, and since I don't have a manual handy i'm not sure which different things this can mean... I had it turn on in the past which turned out to just be to let me know the bulb was out for the rear brake lights/went back off. But this time the bulbs seem to be just fine. I checked master cylinder fluid level - that also seems to be fine.

What else might it be or should I check? What might trip the warning sensor?

 

[Thermo1223]

Parking brake sticking? It's been a long time since I had a Caprice.

 

[Chris142]

Parking brake switch or the proportioning valve is stuck

 

[mk378]

Look for a switch on the master cylinder reservoir, it will turn the light on if it thinks the fluid is low (if fluid level is OK, disconnect switch to see if the light was on because of a faulty switch). That car may not have one though.

 

[paulo57509]

There's no low fluid warning on a '91 Caprice.

Check for fluid leaks at the MC and the wheels - The proportioning valve (GM calls it a combination valve) has a sliding piston within, when there's a fluid pressure differential between front/rear, will slide to one side and turn on the BRAKE light. This usually only happens when there's a leak in the system or when bleeding.

Otherwise, check the parking brake switch (I have no idea whet it looks like).