C0306 code meaning
Transfer Case Motor A or B Circuit
What C0306 means
C0306 is not in the publicly available J2012 lists, and nobody uses it for a ride height sensor. GM uses it in its transfer case module (TCCM) for the two circuits that drive the shift motor: AA1Car's GM table names it Motor A or B Circuit, and bulletins PIP5080 and PIP5080B for 2012–13 Silverado, Sierra, Tahoe, Suburban, Avalanche and Yukon point to terminals at X109 and to connector X3 of the module, which carries motor circuits 1552 and 1553. Gears Magazine describes the 2013–14 Canyon and Colorado: the module powers one motor line, reads the voltage drop on the other and sets the code after four seconds of wrong values; subcodes 01, 02, 04 and F1 mean short to battery, short to ground, open and performance.
C0306 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0306
- Service 4WD message in the driver information centre
- Transfer case does not shift between 2WD, 4WD and low range
Common causes of C0306
- Most likelyLoose, corroded or poorly crimped terminals at the motor or module connector
- PossibleTransfer case shift motor with internal short or open winding
- Less likelyFaulty motor driver in the transfer case control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Transfer case control moduleShift motorTransfer case wiring
What each part of C0306 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 06 | The exact fault in that area. |
What to do next
- Note C0306 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C0306
What does C0306 mean?
C0306 means "Transfer Case Motor A or B Circuit". C0306 is not in the publicly available J2012 lists, and nobody uses it for a ride height sensor. It is a generic code, so it means the same on every make.
Is it safe to drive with C0306?
Drive gently and only to a workshop. With C0306 the car can go into limp mode (reduced power) to protect itself.
Will C0306 fail an emissions test?
C0306 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C0306 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will C0306 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.