Paolo has a K1500
Newbie
I'm a little late coming to this but I am also having the soft pedal issue despite replacing master cylinder, and servicing front and rear brakes. I was about to upgrade the front rotors and pads and replace all of the flexible lines. After reading this thread I did some further research and found this article on the Kelsey-Hayes RWAL system. They pinpoint the dump valve as a common cause for poor brake performance. GM didn't specify a regular brake fluid replacement interval. The dump valve is very susceptible to moisture and any crud in the system can can cause the valve to stick open allowing fluid to leak into the accumulator and allow the pedal to drop.
https://www.aa1car.com/library/abs_kelseyhayes_rwal.htm
Quote:
"If a small piece of dirt or rust gets into the unit, it may prevent the dump valve inside the EH valve from closing. The dump valve will then leak fluid into the accumulator when the brakes are applied. The misrouted fluid allows the pedal to drop, and the pedal may go all the way to the floor without applying the brakes. No ABS warning light or fault code will be found either because the limited diagnostics on this system can't tell if the dump valve is fully closed or not."
After reading this thread I'm unsure if anyone had tried just replacing the dump valve?
I appreciate all the work people have done to try and fix the problem. In fact there has been so much effort for so long that the amount of information is vast and a bit confusing. I'm looking to improve the crappy braking on my truck but I don't want to just throw money and parts at it until something works.
https://www.aa1car.com/library/abs_kelseyhayes_rwal.htm
Quote:
"If a small piece of dirt or rust gets into the unit, it may prevent the dump valve inside the EH valve from closing. The dump valve will then leak fluid into the accumulator when the brakes are applied. The misrouted fluid allows the pedal to drop, and the pedal may go all the way to the floor without applying the brakes. No ABS warning light or fault code will be found either because the limited diagnostics on this system can't tell if the dump valve is fully closed or not."
After reading this thread I'm unsure if anyone had tried just replacing the dump valve?
I appreciate all the work people have done to try and fix the problem. In fact there has been so much effort for so long that the amount of information is vast and a bit confusing. I'm looking to improve the crappy braking on my truck but I don't want to just throw money and parts at it until something works.