Rear tires skid when brakes applied and ABS light is off

[sgosine577]

2007 Mack Granite, CV 713. When I apply the brake, the rear tires lockup and leave skid marks. The ABS light is off. my mechanic put the computer on and there were no faults.  I hear six clicks when I turn the ignition on. I suspect the ABS is not regulating the pressure to the wheels. Changed brakes, drums, slack adjusters, s cams and bushings, the only items remain are the ABS ECU, and the ABS modulating valves (2 each).

Edited June 30, 2016 by sgosine577
new repairs

[hgfdg1990]

 , ticking is normal when u first turn the key on its a self check  even some trucks make a air pumping sound when u turn the key on.Anyways has the brake pedal been cleaned around have seen on a lot of the older dm models would have a mountain full of dirt in the cab build up around the plunger for the treadle valve affecting the stroke and causing it to get stuck, also how long is it taking for the brakes to release the air after you let go of the pedal , have seen clogged diaphrams inside quick release valve preventing air from releasing causing the brakes to stay on after the pedal was pressed. How many axles/tandems you got locking up on ya is my next questionnn and i can help you more also you said the ABS light is off which means there should be no faults or problems with ure ABS system

Edited January 28, 2017 by Bigmackdaddy77

[MackTech]

Does your truck have traction control? If so the traction control valve could be bad.