2021 GMC Yukon Problems: 4 Known Issues

On the 2021-2024 GMC Yukon 6.2L V8 (L87), nHTSA campaign 25V274 covers certain 2021-2024 GMC Yukon vehicles with the 6.2L gasoline V8. Manufacturing defects in connecting-rod or crankshaft components can damage the engine and cause engine failure.

On the 2015-2024 GMC Yukon All engines with Integrated Trailer Brake Control (RPO JL1), the Yukon's Integrated Trailer Brake Control system (RPO JL1) is considerably more sensitive to connection quality than the aftermarket brake controllers it replaced. Rather than simply switching current to the trailer when the pedal is pressed, the Trailer Brake Power Control Module (K133) sends a continuous low-level test pulse down trailer brake output circuit 47 — pin 2, the blue wire on the 7-way. The Chassis Control Module (K38), Chassis Control Module Auxiliary (K38A) or Brake System Control Module (K160), depending on model year, reads the response of that pulse to determine whether a trailer is attached, what kind of brakes it has, and whether the circuit is healthy. Because the module is effectively monitoring circuit integrity continuously, ordinary trailer-grade wiring faults that an older controller would have tolerated now register as hard faults. GM's PIT5509-series bulletins spell out the exact mapping between what the driver sees and what the circuit is doing: a 'Check Trailer Wiring' message with no DTC means an open and/or high resistance occurred in circuit 47 during that ignition cycle; a 'Check Trailer Wiring' message with DTC C1114 and no Service Trailer Brake message means a short to ground on circuit 47; and a 'Service Trailer Brake System' message with C1114 means a short to power on circuit 47 or a poor trailer ground. That last combination is the one Yukon owners hit most, and it is usually caused on the trailer side rather than the vehicle side. The usual culprits are a poor or loose connection at the 7-way, a corroded or water-intruded connector on either the Yukon's hitch receiver or the trailer plug, a trailer ground wire bolted to a painted or rusted frame rail instead of bare metal, chafed brake wiring rubbing through against an axle or frame crossmember, or excessive harness length that lets the plug work loose while driving. Salt-belt vehicles and trailers that get dunked at boat ramps are heavily overrepresented. Because a marginal ground can hold up under light braking and fail under load, the fault often shows up mid-trip on a grade, exactly when the trailer brakes matter most. GM is blunt about where the problem usually lies: it notes that most trailers with these wiring issues do not have high standards for wiring, connections, splices and routing compared with automotive practice, which is precisely why a module that continuously monitors circuit integrity trips on them.

On the 2021-2023 GMC Yukon, nHTSA campaign 24V797 covers certain 2021 diesel GMC Yukon vehicles. A transmission control valve can fail and cause the rear wheels to lock.

On the 2015-2025 GMC Yukon, the power retractable running boards available on 2015+ Yukon and Yukon XL are a common failure point. The electric motors and gearboxes corrode and seize, especially in salt-belt states. Boards get stuck in the out position (creating a road-clearance hazard and trip risk) or refuse to extend. The wiring harness connections at the running board motors corrode. GM has released multiple updated motor designs, but corrosion in the mechanical linkage pins also causes binding. Repair cost is $800-2,000 per side if both motors fail.