I have a 1997 Blazer LS 4.3 engine and ABS
Not long ago my ABS light came on and brake light came on and stayed on, my brakes didnt work well I had to push all the way and I felt vibration. I disconnected the ABS wire from pump and ABS light went out and brake light is out and front brakes are working good but back brakes are very weak. Yes the brakes are good, no, there are no codes to be found (Per dealership) No, dealership didnt tell me whats wrong. yes, the brakes have been bleed. But still the back brakes apply but very weakly.. No, the brake lines are good, some are new.
I thinking the ABS pump went, or master cylinder. Any thoughts?
If ABS pump any thoughts where to find a cheap one?

 

Proportion valve on the abs module is bias to front brakes. To center valve open front brake bleeders and work brake pedal slowly till light goes out on dash . Then close front bleeders and do normal bleeding on back brakes