No rear brakes on 1st pump
As the title describes and at the same time the brake light will come on. Also the brake pedal is a little deeper than normal. If I pump the pedal twice or more, then all is well.
My guess is the proportioning valve is not functioning correctly, but I already guessed at a master cylinder and was wrong. So I figured I'd ask the experts before I guess poorly ..... again lol.
Vehicle is a '90 GTA Firebird with stock 4 wheel discs.