1981 C10 Brake Bleed problem

[Jamie]

My brake warning light went on a few weeks ago. The only symptom of failure was that the truck would pull a little to the left on braking. Otherwise, no leaks and the master cylinder seem to check out okay. In an attempt to solve the problem or make it show itself again, I decided to simply bleed the system and hopr that the brake warning switch re-set itself. No such luck. In the midst of bleeding the right front caliper, no fluid came out.

I have read that in power bleeding the system after the warning light has come on, the proportioning valve will actually shut a circuit down. Is this your experience?

The instructions that I've found in Clymer's for re-setting the plunger/switch are confusing and do not match the proportioning valve in my truck (probably written by someone who has never done the work). Does anyone know what I can do? Help!!!! Thanks in advance.