Hi,

I read a few thread on subject but can not pin point the problem. My brake light comes on intermittent. It comes on and stay on for couple of second to couple of minutes, sometime blinking and diming. My foot pedal switch is ok, the fluid level is OK. It does not come on often.
Does the ajustment of rear brake changes anything?
I am going on a trip, is there any danger?

Tanks, Mike

 

My break light used to come on sometimes when the vacuum pressure (that runs the power breaks) got too low. It did the same thing your describing. The light would come on and then go off a few minutes later. Usually it came on at a stop light or when the truck was at idle and the would go away when the RPM when up. I turned up the idle a little and it seems to have fixed the problem

 

My break light used to come on sometimes when the vacuum pressure (that runs the power breaks) got too low. It did the same thing your describing. The light would come on and then go off a few minutes later. Usually it came on at a stop light or when the truck was at idle and the would go away when the RPM when up. I turned up the idle a little and it seems to have fixed the problem.

You might want to check your vacuum tubes/pump etc for leaks. I can tell you from when all my belts broke when you loose power breaks it is VERY hard to stop.

 

I will check this out. Today it is raining again an agin and agin

I let you know

 

Three things cause the brake light to turn on.
Brake system out of balance, bleed front or rear brakes to turn it off.
Low vacuum, pump could be ready to die, leak somewhere in the system.
Parking brake pedal not all the way up against the switch tight.

Since the first option comes on and stays on I think you could eliminate that one.

Vacuum related could be bad news, it is real hard to stop if you lose vacuum.
Check it with a guage and see if it is fluctuating a bunch. Another thing is the low vacuum switch could be going bad, mine is on the right hand inner fender well.

I think the return spring on the parking brake is not holding the pedal up tight against the switch. I am assuming that the parking brake light and the brake warning light on a 91 is the same light like it is on my 86. Mine does that from time to time exactly like what you are describing. Put your toe under the parking brake and pull it up, if it goes off then that is the problem.

If the rear brake shoes are out of adjustment real bad, they may be triggering the balance switch, but normally it is not going to reset itself that easy.