An owner of a 2021 GMC Sierra is now seeking answers after changing the truck’s front brake pads for the first time and seeing several warning messages upon starting.
The owner shared their issue in a post on the r/MechanicAdvice subreddit, explaining that after changing the brake pads, they soon received warnings about reduced steering assist, the brake system, and electronic stability control. They also said the check engine light and brake warning light are on.
Worse, the truck displayed a brake system failure warning on its dashboard and indicated the top speed was limited to 62 miles per hour. The owner admitted they had not disconnected the battery before replacing the brake pads.
They also said that although the brake pedal felt normal in park, they had not driven it and wanted to know whether it would be safe to do so.
An Unexpected Warning
Changed Front Brake Pads, now this? Help.
by
u/Curious_Pontiff in
MechanicAdvice
With all the warnings popping up after replacing the brake pads, the owner questioned what exactly had gone wrong during the process. They also asked whether disconnecting and reconnecting the battery might fix the warnings or whether they should take the truck to a repair shop.
One commenter gave a thorough explanation of what they believed might be happening, suggesting that the truck’s braking system could require a more involved procedure. They said the vehicle might need its diagnostic codes cleared, the battery disconnected, and the brakes bled using a pressure bleeder.
The comment also suggests a scan tool would be needed to run a hydraulic system pressure test before pressing the brake pedal again. But they warned if this failed, the truck could potentially require replacement of the master cylinder assembly, which they estimated could cost around $4,000.
However, this was just a recommendation, not an official diagnosis of the GMC Sierra’s problem. The exact cause of the warning messages is still not clear.
Others Disagree on What Could Fix the Problem
Not everyone agreed with the first commenter’s assessment. Others suggested that a simple code clear could take care of the issue.
Another commenter shared a similar experience with their own 2021 GMC Sierra 1500 after replacing the front brake pads. They added that they hadn’t disconnected the battery before starting the work. After bleeding and pumping the brakes, their truck began displaying warnings because the system appeared to detect a leak.
But according to the comment, the problem eventually went away on its own after a couple of days of driving. While that offers one possible explanation, it does not establish that the same thing happened to the original poster’s truck.
The safest course of action is probably to leave the truck parked, consult a qualified mechanic, have the braking system inspected, and retrieve diagnostic codes.
But for now, it remains unclear what the cause of the warnings actually was or if the warning took their vehicle to a repair shop.