2004 Silverado 1500 crew cab 143" wheel base. I can't get a descent brake pedal. It's halfway to the floor and very soft. This is not my first brake job. Items that I have replaced are; dorman stainless steel brake line kit, all brake hoses, power stop brakes, calipers (front and back), dual piston (front and back) came stock on this truck, JC4, new disc, new pads, new master cylinder, new vacuum power booster, ABS pump with a used ABS pump twice. Power bled system, activating the ABS module with a Foxwell NT630 plus and a GM tech 2 scanner, showing no codes. Clear fluid flows from all four calipers with power bleed and manual pedal bleed. And yes, the calipers are on the correct side with the bleeders on the top. The only thing I haven't replaced is the ABS module, but I'm getting no codes for it, and the proportioning valve, but clear fluid flows out of all 4 calipers with the power bleeder and the pedal bleeding. I'm pulling my hair out and I have used 4 gallons of brake fluid already. There are no leaks in the system. I'm now desperately asking for help!

 

Update: I have benched the used ABS pump thinking it was the source of this problem. I opened one of the extra used ABS modules and removed one of the electromagnets from the board that operates the valves. Holding the ABS pump assembly in the vice, placing the electromagnet over a valve. Using a Car battery I charged the electromagnet. Not knowing which polarity to use switching from red on the right to red on the left alternating polarities on the magnet. Moving from valve to valve listening for indications that they were working (a clicking sound) and marking which ones did. Setting that ABS pump aside and doing the same with 2 another used ABS pump, marking the good valves as I went. It was clear between the three used pumps that all had some valves that did not click, but not in the same locations. My deduction: All should have been indicating a click. I also was able to finding a video on YouTube stating the same. Thinking the valves could be freed up some PB Blaster was used, saturating the ports where the brake fluid goes, and activating the corresponding valves with the electromagnet. This worked air bubbles out with the valves that were working. With nothing to lose heat was applied to the aluminum housing, after backing the bolts out of the motor so heat would not be transferred to it and the plastic insulator between motor and valve body. Care was taken to not over heat valve body, not knowing what could be inside that could be destroyed. This operation did loosen a valve (it started clicking) but stopped as it cooled = no luck. It was hard for me to get my head around that I could be lucky enough to three bad pump assemblies, but guessing I did. I have ordered a re-manufactured Pump/valve assemblies.


pump assembly which should be in next week.

 

Wow! That is a lot of detective work. Hopefully the rebuilt ABS module will solve all your issues, and has all the valves in working order.