General Motors is investigating an all-wheel drive fault affecting some of its newest crossovers, including the Chevy Traverse, GMC Acadia, and Buick Enclave. This issue, outlined in service bulletin PIT6479A dated March 2026, can trigger an “All-Wheel Drive Service” or “4WD Service” message at startup, while disabling the AWD function.
These provisions apply to 2024-2026 GMC Acadia and Chevy Traverse units, as well as 2025-2026 Buick Enclave models equipped with the F48 AWD system. On affected vehicles, technicians may encounter diagnostic trouble code U3000 Sym 92 stored as a current code or history code in the K47 Rear Drive Control Module.
GM stated clearly that “engineering is investigating” the root cause. Meanwhile, automakers have issued clear guidance to dealers: do not replace the rear drive control module. According to the bulletin, “the new module will not solve the problem and will function in the same way.”
Instead, the specified improvements are procedural in nature. Technicians were instructed to disconnect the battery for 20 minutes, reconnect it, and complete a full power cycle. After that, they should clear all diagnostic trouble codes using GDS2. This reset restores AWD operation, although only temporarily. GM warns that “the error may or may not occur again” until a permanent software fix is available.
Owners can continue to drive the vehicle despite the warning message, but the problem is expected to recur. The temporary nature of this repair underscores that this is not a hardware failure, but likely a software-related anomaly in the AWD control system.
The bulletin emphasizes that it is intended for trained technicians, noting that proper diagnosis and repair requires special tools and procedures. Vehicles repaired under warranty are eligible for a 0.4 hour labor operation associated with the reset and code clearing process.
GM has not given a timeline for a final resolution. The company indicated that the bulletin will be updated once engineers complete their investigation or release an official fix. For now, the situation remains under control but not resolved, and GM is opting for a measured, service-based response while working toward a permanent correction.
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