Chassis, generic

C0308 Transfer Case Motor A/B Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

None of the publicly available J2012 lists contains C0308, and no source links it to a ride height sensor. GM uses it for the transfer case shift motor: PIP5094 lists the number, AA1Car's GM chart labels it Motor A/B Circuit Low, and Dorman's guide for its replacement motor covers 1998–2005 S10 Blazer, Sonoma, Tahoe, Suburban, Yukon, Silverado, Sierra, Escalade, Avalanche and related trucks. The transfer case module sets it when it finds motor control line A or B shorted to ground, or when the feedback voltage on those lines is far too low. Once stored, the module stops every 4WD shift and lights Service 4WD. The sibling codes C0309 and C0310 cover a high voltage and an open circuit on the same lines.

Likely causes

Motor control wire A or B chafed against the frame and grounded
Shift motor internally shorted
Transfer case control module output stage faulty

Symptoms

  • Service 4WD lamp on
  • No shifting into or out of four-wheel drive

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–700
Time0.5–2.5 h

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

Parts involved

transfer case control moduleshift motortransfer case wiring

Related codes

C0306C0310C0327

References: aa1car.com, dormanproducts.com, static.nhtsa.gov.