I have a 2000 Chevrolet Silverado z71 4x4 with 83,000 miles. I was pulling in to parking spot at the bank, applied brakes to only find that they were harder than a rock and would not stop. I run into a light pole, smashing my bumper, valance, cracking grill, buckled the fender and ruined the headlight brackets. I backed it up and applied the brakes and they were fine all of a sudden. I crept home slowly and they seemed to work ok again.
I am mechanic by trade and I checked everything from rotors, abs sensors, lines, brake booster, fluid, calipers and master cylinder. I have replaced master cylinder along with proportioning valve and still have the hard brake problem every now and then. There is no apparent reason for the timing of the pedal getting firm. I have tried it in rainy weather, cold weather and hot humid days and it does not make a difference due to weather. I have not been able to drive my truck for one year now since Dec. 26th of 2010. However, I have crept around the corner to the store for groceries to keep it in running order until I can further figure out the problem. I have one two more possibilities that I believe might be causing the erratic problem. One is the abs control module and the other is the abs modulator valve.
In 42 years of mechanics, I have never run into such a problem that is clearly a defect in the repeated production of these vehicles. I have not repaired the damages as of yet and will not repair the bodywork until the brake problem is restored to normal. This is a very dangerous problem that has been overlooked and brushed under the mat by these manufactures. The sad thing is when somebody gets killed, and then a lawsuit will get these white collar guys off their duffs to do something. They should be ashamed of so many Chevy trucks being defective. I would be glad to help in a class action lawsuit to help correct this problem to restore the safety of these trucks and there passengers because I believe 100 percent that this is a defective abs brake system effecting many Chevrolet trucks.
