Brake Light

[flatford39]

Got my new master cylinder installed today and every thing seems to be real good. Plenty of pedal etc. Truck stops well. The brake light although is still on. Not sure what this means. I bench bled the MC before installing and bled the wheel cylinders as recommended. Right rear, left rear, right front and finally the left front.

Any ideas on what might be causing this. The truck is a 1980 K10. Disc brakes on the front and drums on the rears.

 

[chengny]

Normally I would think that it's the proportioning/combination valve that is throwing the brake warning and it needs to be reset. But the fact that you were able to fully bleed all the brake circuits would indicate that the P/C valve piston is properly centered.

Any chance that the parking brake is hanging down low enough to close that switch?

The dash brake warning light can be illuminated by either the P/C valve or the parking brake.

As a test, pull the connector off the P/C valve and note whether the dash light goes out.

If it stays on, check the parking brake.

If it goes out, the P/C valve's internal switch is causing the warning light. Look into how to reset it.

 

[flatford39]

Thank you...that is the advice I was looking for. I have a suspicion it is the parking brake.