Before i took my truck, an 80' f100 with a 302, off the road last fall the brake light in the dash came on. I thought it was because the brakes were terrible. My fronts looked decent, and i changed the backs. My brakes are now great, but the dash brake light is still on.
Anyone come across the same problem or have suggestions? Thanks!
I agree, porportioning valve could be stuck. Try resetting it, and also bleed the brakes if air could have gotten into the system with the brake repair.
The 1984 year model is the first year that the brake warning light was hooked to the parking brake pedal as standard, so it's almost positive it's not that problem for your 1980, unless someone added it. There was a dealer kit for this before 1984, so just check the parking brake pedal for added wires etc...
If you want to make sure it is the proportioning valve causing the problem, just disconnect the wire going to the valve. If the light goes out, then that is the problem. It has a plunger that separates the front brake system from the rear. If you have a failure in either system, the pressure difference pushes the plunger off center and grounds the wire which lights the dash light.
The light is a safety feature. Disconnecting it or making it inoperable is not a wise idea.
There are also insurance repercussions to concider if you get in an accident. Your insurance does not have to pay, and you could be liable for any accident you are in, your fault, or their fault, for tampering with safety equipment.