C0308

DTC C0308

Circuit Description
The transfer case motor is a bidirectional, permanent magnet, D.C. motor. When energized, (through Motor Control A or Motor Control B. the ground is provided by the opposing Motor Control circuit and then grounded through the transfer case shift control module ground circuit), the motor, through a series of gears, rotates a shaft which moves the mode and range forks to shift the transfer case between 4H, AUTO 4WD, 2H, N. and 4L ranges. While the transfer case motor is energized the transfer case shift control module also energizes the solenoid for the transfer case lock. The motor lock is disabled (locking action released) and free turning of the transfer case motor and sector shaft is then allowed.
This DTC detects a short to ground in Motor Control A or Motor Control B CKT.

Conditions for Setting the DTC
^ The system will test the motor circuits:
- First, the system checks for unwanted voltage.
- Then, the system supplies voltage on one circuit and reads the voltage back on the other.
^ If the system detects a problem with the circuits, the DTC is logged.
^ The transfer case shift control module senses a low voltage return in Motor Control A or Motor Control B when a high voltage is expected.

Action Taken When the DTC Sets
^ All shifting will be disabled.
^ The SERVICE 4WD indicator will be latched on for the remainder of the current ignition cycle.

Conditions for Clearing the DTC
^ The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists.
^ A history DTC will clear after 100 consecutive ignition cycles without a fault present.
^ History DTCs can be cleared using a scan tool.








Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible motor noise when the encoder motor operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Tests for a short to ground in the Motor Control A circuit.
4. Tests for a short to ground in the Motor Control B circuit.
5. Tests for a higher than normal resistance in the Motor Control A and B circuits through the module.
6. Tests for a short to ground in the encoder motor windings.
7. Tests for continuity across the motor circuit. Resistance readings vary depending on the location of the brush contact inside the motor assembly.
8. Tests Motor Feed A circuit for a short to ground.
9. Tests Motor Feed B circuit for a short to ground.
10. Tests Motor Feed A and B circuits for an open or high resistance.