Brake Warning Light

S

sockmonkey

New member
Hello, to start off I have a 74 Scout II, 345 v8, front disc, rear drum. I recently had a leak in the pass. Rear wheel cylinder and replaced it. After that I noticed that the brake warning light (in the speedo) would not shut off. I bled all 4 brakes, to ensure that the pressure was equal, however the light is still on. I feel like I am missing something simple, however I have no idea what it is. The pedal feels okay, but seems like it grabs less than before.

Can someone please help? Thanks!
 
There is a switch in the proportioning valve that controls the light. Normally it resets after good pressure is returned to the system. I have had them stick from time to time and had to take it apart and clean.
But your first step would be to bleed the system again Mainly because you said it does not feel the same as it did before. Once you have re-bled the system start the truck and "stand" on the brake pedal a couple of times and set if it resets the light. If it does not you May have to take the valve a part.
If you look at the valve there is a wire connected to the top of the valve. If you remove the switch that wire is connected to you can see a small plunger on that switch that has to fit in a small groove in the piston of the valve, they have to line up.
There is also a pin on the end of the valve that moves with the piston you might get lucky by pressing that pin to see if it will reset the piston.
There is really not much to the proportioning valve so they are easy to dis-assemble, but you would need to bleed the system again.
If you use the search here you can probably find a post on the best way to do this, but this is what I have done and it worked for me.
Ron
 
I am missing something simple,
Click to expand...

Did you press the front button on the combo valve?(some call it the proportioning valve)

whenever the front axle, with disc brakes, is bled; the button on the combo valve is pressed to bypass the metering valve feature. That way you'll get full flow when bleeding the calipers. Try a bleeding on the front only and see if that gets the system back to "normal". If not, than do all four.

Sometimes the electrical switch May need to be removed to center the spool that triggers it. Nothing will leak out. Just make sure that it and anything around is clean so no debris falls in. Apply the brakes and re-install the switch. While the switch is out you could test it pushing the little plastic rod. The switch body has to be grounded for the light to work.
 
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