Chassis, generic

C0374 4WD Drive Coupling

Check engine lightUsually off

EmissionsNot relevant

Drive cycleNot required

Limp modePossible

No publicly available J2012 list carries C0374; GM uses it in the transfer case control module of its 4WD trucks and SUVs, and PIP5094 names it among GM chassis codes. Dorman's sheets for the S10, Blazer, Astro and Safari, the Trailblazer, Envoy and Isuzu Ascender call it General 4WD Failure: in Auto 4WD the module notices rear wheel slip, commands torque to the front axle and still sees the front and rear propshafts turning at different speeds. After ten attempts that fail to couple the front drive it stores the code. Auto 4WD is then unavailable and Service 4WD stays lit until the next engine start. The fault thus points to the coupling path as a whole, encoder motor, clutch and speed sensors, rather than one circuit.

Likely causes

Encoder motor too weak or sticking, so the clutch is not applied

Front or rear propshaft speed sensor or its wiring giving false values

Worn transfer case clutch pack or wrong fluid

Tires of unequal size or pressure faking a speed difference

Symptoms

Service 4WD message until the next engine start
Auto 4WD does not engage, rear wheels spin on slippery ground

Repair estimate

DifficultyHardWorkshop job

Parts and labour€50–1,500

Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

awd couplingtransfer case control moduleencoder motor

Related codes

C0376 C0387 C0327

References: dormanproducts.com, dormanproducts.com, dormanproducts.com, static.nhtsa.gov.