Our 1997 GMC Sierra locks rear wheels suddenly

Emergency brake cable is to tight or rusted and holding them to closed. the garage should have caught this. Find another garage.

Have you been bleeding with a vacuum bleeder tool or the conventional way. A vacuum bleeder gets out more air provided that everything else is done correctly.Like the correct wheel sequence depending on weather you have rear wheel anti-lock only or four wheel abs.Refer to a Haynes repair manual.

need more info---did you have brakes worked on, did it happen all of a sudden???

does it stay at floor if tou pump it?

Sounds more like a brake problem.have you pulled the brakes and checked for a hanging up ebrake etc?

Replace the shift lock solenoid whichis located by the shifter inside the truck.It keeps the shifter locked in place until you press the brake pedal to shift

Make sure master cylinder is full of brake fluid, then check to make sure rear drum brakes are adjusted properly. With rear wheels off the ground, truck in neuatral, wheels chocked, by hand spin wheel it should have a firm drag to it. If not they need to be adjusted.

check wheel bearing... and make sure that the metal shims are installed with the pads. they prevent noises

Hi First of all check the adjustment on the rear wheel thats sticking sometimes the brake pad comes away from the metal it is fixed to this maybe the case on your vehicle, the make & year of vehicle would help further but I a sure you got something to check now. Please leave me feedback, Malcolm Campbell.

okay you had brake work done!!! "THINKING" that was the problem originally right rear wheel locking up! okay,,, so doing brakes has not solved your problem! I would maybe look into rear end bearing??? do you have any load road noise from rear and do you have rear end fluid in differential? question to you was the baking plate ""WET"" looked damp? or moister get at it!??? seal might have leaked all fluid out??? all the above would be good place to start! good luck I hope this info helps you out.Happy new year.