I have a 2003 Chevy Silverado 1500. When I start the truck, and am on gravel or a slick spot and step on the gas, the rear tires may slip but when that happens, a wheel locks up and is hard to get unstuck. Any ideas?
that may be a tough one. one thing you could do is have a floor jack somewhere close so you can jack the rear axle up when it happens and find out which wheel is locking up. also, if a scanner is available, check your ABS brake. See if a problem exists with a solenoid getting stuck.
parking brake could also be a problem. A rear axle seal might be leaking on to the park brake shoes.
I would take it to a shop and have them keep it overnight. Have them test it and see if they can duplicate the condition. Once they do that they can jack up the rear axle and see which wheel is locking up. Once they find which one is locking up, or if it is both of them, they can check to see if a hydraulic part is a problem or a mechanical part is a problem. If one wheel is locked up, open the bleeder screw and see if hydraulic pressure is holding the brake on. If brake fluid shoots out and then the wheel is free then a brake hose may be bad or the anti-lock brake may be the problem. If opening the bleeder screw does not free up the wheel, they will need to find out if the parking brake, the caliper piston getting stuck or something with the axle is jammed up.