reset proportioning valve (brake dash light on)

[minagle]

My 1982 GMC 2wd C1500's brake light came on on the gauge cluster. The fluid was a little low. I checked the brake lines, and found the line on the rear axle going to the passenger rear wheel was leaking. I was lucky enough to find someone selling pre-bent lines on ebay, and ordered a replacement set for the rear. I only replaced the one that was leaking. I bled both rear wheel cylinders. There was definitely air in the line I replaced, but got the air out of the system. I pulled all four wheels earlier in the week. I did not see any leaks from the calipers or wheel cylinders.

The brakes feel better, I think. I'm used to driving a modern car, so I think the brakes feel normal for a 35 year old truck.

I drove around a little, and the brake light stays on. I disconnected the wire from the proportioning valve to verify that is what is triggering the brake light, and it went out when I unplugged the connection. Brake fluid in MC is topped off.

I don't see any other leaks in the lines. Do I somehow need to reset the proportioning valve? Any other ideas?

 

[chengny]

My 1982 GMC 2wd C1500's brake light came on on the gauge cluster. The fluid was a little low. I checked the brake lines, and found the line on the rear axle going to the passenger rear wheel was leaking. I was lucky enough to find someone selling pre-bent lines on ebay, and ordered a replacement set for the rear. I only replaced the one that was leaking. I bled both rear wheel cylinders. There was definitely air in the line I replaced, but got the air out of the system. I pulled all four wheels earlier in the week. I did not see any leaks from the calipers or wheel cylinders.

The brakes feel better, I think. I'm used to driving a modern car, so I think the brakes feel normal for a 35 year old truck.

I drove around a little, and the brake light stays on. I disconnected the wire from the proportioning valve to verify that is what is triggering the brake light, and it went out when I unplugged the connection. Brake fluid in MC is topped off.

I don't see any other leaks in the lines. Do I somehow need to reset the proportioning valve? Any other ideas?

There is a procedure (it involves loosening a bleeder on the circuit you did not repair and applying the brakes - this should recenter the spool, open the path to ground and extinguish the warning light).

But before you go through that whole process, just try driving down the street slowly and then SLAMMING the brakes on. That is all I have ever needed to do to reset the spool.

 

[minagle]

Thanks - a hard slam on the brakes reset it. It's the simple things. Thanks again!

 

[Coal creek Chris]

There is a procedure (it involves loosening a bleeder on the circuit you did not repair and applying the brakes - this should recenter the spool, open the path to ground and extinguish the warning light).

But before you go through that whole process, just try driving down the street slowly and then SLAMMING the brakes on. That is all I have ever needed to do to reset the spool.

Do you think the Slamming procedure would work to re-set the spool if the truck is on stands with the wheels off? I could put it in gear, letting the rear wheels turn and simulate about 10-20 mph, then slam on the brakes.