Chassis, generic

C0387 Transfer Case Unable to Complete Shift

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0387 is absent from the publicly available J2012 lists. GM uses it in its transfer case control module as Unable to Complete Shift; there is no evidence of a position sensor code. PIP5003C for 2010–13 Silverado, Sierra, Tahoe, Yukon, Avalanche, Escalade and hybrids explains that once a range change or a slip correction has been commanded, the module watches the shift shaft and sets the code when the motor has not begun to move it within 50 ms; heat, cold and supply voltage influence this. If it is history only and cannot be reproduced, a slow encoder motor is the likely culprit, not the module. PIP5080 has technicians check terminal fit in plugs X109 and X3. Per PIP5089A, if the fault is still present at the next start the failed relearn sets C0569 instead. Dorman adds that the module may default to 4HI or 4LO.

Likely causes

Encoder motor too slow to start moving the shift shaft
Poor terminal fit at the module connectors (GM X109, X3)
Low supply voltage or extreme temperatures during the shift
Mechanical binding inside the transfer case shift mechanism

Symptoms

  • Service 4WD message, often intermittent
  • Requested range or mode is not reached
  • Transfer case stays in a default 4HI or 4LO

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–800
Time0.5–3 h

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

Parts involved

encoder motortransfer case control moduletransfer case position sensor

Related codes

C0306C0327C0374

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