C0374 on GMC
Transfer Case / Automatic 4WD System Malfunction (manufacturer-specific)
C0374 on GMC vehicles indicates transfer case / automatic 4wd system malfunction (manufacturer-specific). Au7o has documented this code across 1 GMC model — most commonly on Sierra 2500HD. C0374 is a manufacturer-specific chassis code (commonly seen on GM four-wheel-drive vehicles) that generally indicates a general malfunction in the transfer case / automatic four-wheel-drive control system. When it sets, the Auto 4WD mode is typically unavailable and a 'Service 4WD' message may appear. Because the exact subsystem can vary by maker and model, the precise fault should be confirmed with a factory-level scan tool. This code affects drivetrain/4WD operation rather than braking. Typical repair costs on GMC range from $250 to $900, depending on the specific model and root cause.
Common Causes of C0374
- •Faulty transfer case control module
- •Transfer case encoder/actuator motor fault
- •Damaged wiring or connectors in the 4WD circuit
- •Mode-select switch fault
- •Low system voltage or poor ground
- •Mechanical fault within the transfer case
- •Software/calibration issue in the 4WD module
C0374 on GMC by Model
GMC Sierra 2500HD(1 issue)
- Transfer Case Encoder Motor and Selector Switch Failure Causing "Service 4WD" and Loss of 4HI2001-2014
The electric-shift NV246/NV263 transfer case on Sierra 2500HD trucks is positioned by an encoder motor mounted to the case, with a sensor ring inside it reporting shaft position back to the Transfer Case Control Module. Moisture and road salt corrode the encoder motor and its sensor ring, and the dash selector switch itself develops open contacts. When the TCCM loses a valid position signal it illuminates "Service 4WD" and refuses to shift. The classic pattern owners describe is a truck that will still drop into 4LO but will not engage 4HI, because the module can drive the case to its travel extremes but cannot stop it at the intermediate position. C0327 is the code that identifies it.
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View C0374 across all makes →Frequently Asked Questions
What does C0374 mean on GMC?▼
C0374 stands for "Transfer Case / Automatic 4WD System Malfunction (manufacturer-specific)." C0374 is a manufacturer-specific chassis code (commonly seen on GM four-wheel-drive vehicles) that generally indicates a general malfunction in the transfer case / automatic four-wheel-drive control system. When it sets, the Auto 4WD mode is typically unavailable and a 'Service 4WD' message may appear. Because the exact subsystem can vary by maker and model, the precise fault should be confirmed with a factory-level scan tool. This code affects drivetrain/4WD operation rather than braking. On GMC specifically, this code is documented across 1 model.
What causes C0374 on GMC vehicles?▼
Common causes on GMC: Faulty transfer case control module, Transfer case encoder/actuator motor fault, Damaged wiring or connectors in the 4WD circuit, Mode-select switch fault, Low system voltage or poor ground. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix C0374 on a GMC?▼
Repair costs on GMC range from $250 to $900, depending on the specific model and root cause.
Which GMC models have C0374 documented?▼
Au7o has documented C0374 on 1 GMC model: Sierra 2500HD.