Brake warning light won't stay off

[Jakes-66-K10]

My warning light used to work as it should, when starting the truck it would light up when cranking then stay off. However once in a while it would stay on, but then return to normal and I'd forget about the problem. It's slowly gone from an intermittent problem to a constant one now, the light always stays on. It's been such an annoyance I've just disconnected the wire from the prop valve.

I'm confused what activates the warning light? I thought it was if your fluid got low, or you had air in the proportioning valve. But I have bled my brakes a number of times, and they have been bled a number of times recently by different auto shops here. What else would cause the light to stay on when connected to the prop valve?

[truckster]

I had that problem before. I think the only way to fix it is to replace the prop valve.

[da-burb]

Your brake light comes on when there is unbalanced brake presure between your front and rear brake circuts. It can mean a loss of presure in any number of places from the master cylinder down to the wheel cylinders/calipers.

If you don't have a real problem with any of your brakes you can reset the sensor. Push down on your brake pedal as hard as you canand then a little harder. This will even out the presure switch and it should go out. If it doesn't you either have a real problem or there is a slim chance it went bad and needs to be replaced.

[nu2-72]

Their is also a little tool that is used to bleed the brakes on these trucks. I just threw three of them in the shop this morning.
It is a little "L" shaped bracket. You loosen the front prop valve bolt, slip this in place to depress the prop. plunger and tighten the bolt down. This allows one person to bleed the brakes and bypass that valve and get balanced pressure at bleeding. No air. Then you remove it and check as da-burb states.
If you are not bleeding using this or a helper to depress that button, try it.
Want a pic?

[70rs/ss]

Another take on this deal is that youe ebrake switch is not depressed all the way. I found my switch had moved away from the ebrake peddle so that the switch did not close the circuit all the way, thus the light stayed lit. Could be?!

[Jakes-66-K10]

nu2-72, yeah a pic would help. All the brake bleeding that has happened, I don't think anyone was aware you had to press a button on the valve. Sounds like you need 3 people to properly bleed a system? Hmm...

70rs/ss what ebrake switch are you referring to? The entire ebrake system is mechanical? I'm lost?

[70rs/ss]

Originally Posted by vortexofpain

nu2-72, yeah a pic would help. All the brake bleeding that has happened, I don't think anyone was aware you had to press a button on the valve. Sounds like you need 3 people to properly bleed a system? Hmm...

70rs/ss what ebrake switch are you referring to? The entire ebrake system is mechanical? I'm lost?

There is a switch located on the top of the ebrake peddle as a reminder that the ebrake is on before you drive off. Look above the peddle and you should find it.