One problem related to brake master cylinder has been reported for the 2003 GMC Sierra 1500. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 GMC Sierra 1500 based on all problems reported for the 2003 Sierra 1500.
Pulling to a stop in my driveway my brakes slowed the truck and then completely gave way with the pedal hitting the floor. I stomped on the emergency brake pedal to keep from hitting the porch. I am so lucky to have that happen at low speed off the road. That could have been a tragedy on the highway. Turns out that my brake lines are severely rusted and one of the 2 lines coming off the master cylinder now has a pinhole leak immediately above the frame where it bends 90 degrees to go back to the abs manifold. Applying the brakes just squirts fluid out of the line. I thought a single failure was supposed to result in reduced braking power, not complete loss of brakes. Note that my truck is in otherwise great shape and I simply had no idea. It is clear that the NHTSA has been bamboozled by gm. Brake lines are a critical life safety system, installed on and in some places in the chassis before the vehicle body and bed are attached. It is not routine maintenance to rinse the brake lines let alone replace them. Gm pushing this back on the customer is complete bs. You can buy nylon coated or stainless steel brake lines for less than 100 $. The incremental cost to go from steel to something that would last the operational life of the vehicle is less than 50 $. I'm waiting on an estimate from my non-dealer shop, but a dealer charging 3600 $ is not surprising considering the amount of labor that must be involved. The NHTSA decision on the issue is unconscionable. Guess it might have been different if they had run over a child at a crosswalk or if their child was mowed down by corporate greed. Hopefully that never happens, but with so many rotting gm trucks on the road, we will have to keep our fingers crossed.