Changed rear drum brakes 2000 c3500 1 ton dually. Bleed all brakes ok disc on front. Test drive and left front wheel locks up and then releases during panic stop under 20 miles per hour. seems OK at higher speeds. Replaced left front caliper and disc pads on both front wheels, same issue with the left front wheel locking up. front brakes release as they should as soon as pedal is released and truck drives normal with good brakes all around. Only happens on panic stop at low speed.

Left wheel speed sensor maybe?
Thanks for any ideas. John

 

the abs should stop the wheel from locking up...when lock up is close to occurring the abs should dump pressure to that wheel and you would hear the abs pump cycle and you should feel the brake pedal pulse. if what I described is occurring at slow speeds you have signal drop out from one of the wheel speed sensors. try to remove the sensor from the hub...any that are stuck in place due to corrosion need to be replaced.

 

Thanks for the reply. Today I disabled the ABS system by pulling the fuse. Doing a panic stop at low speed the left tire still locks up(skids. Would the wheel speed sensor still function with the ABS disabled? Thanks again for the reply.