Symptoms
The truck pulls to one side without warning. GM's wording: "unintended activation of the driveline-protection system will cause unintended braking on the wheel on the opposite side of the failed sensor, causing the vehicle to pull to one side unexpectedly." It happens in a narrow band — between 41 and 60 mph, in four-wheel or automatic mode — which is exactly the speed at which a sudden pull is hardest to correct.
Likely cause
Not the brakes and not the sensor alone. GM's account: "if a wheel-speed sensor fails, while the vehicle is traveling between 41 and 60 mph in four-wheel or automatic mode, the Electronic-Brake Control Module (EBCM) software may activate the driveline-protection system." The sensor failing is ordinary; what was wrong is what the software did about it. That is why the remedy is a reprogram rather than a part.
How should it be checked?
Run the VIN at nhtsa.gov/recalls. If 19V-761 shows open, a dealer reprograms the brake control module free of charge and recalls have no expiry. If the truck is not in scope, the recall tells you nothing about it either way — but a truck that pulls under braking still needs looking at for the ordinary reasons.
How can you check it yourself?
On a straight, quiet road at around 45–55 mph, ease off the wheel briefly and feel whether the truck tracks straight. A pull that comes and goes is more interesting here than a steady one, which is more likely alignment or tyres. Then check the VIN, and check the axle ratio from the RPO code sticker in the glovebox rather than guessing.
The question to ask the shop
What is the axle ratio and is this truck four-wheel drive? Has recall 19V-761 been completed on this VIN? Has a wheel-speed sensor ever been replaced, and has an ABS or traction warning light ever come on?
