C0309

DTC C0309

Circuit Description
The transfer case encoder motor is a permanent magnet DC motor and gear reduction assembly. The encoder motor is controlled with a Pulse Width Modulated (PWM) circuit within the transfer case shift control module. This circuit consists of a power supply relay (Motor Control A) circuit that supplies voltage to the motor. The Motor Control B circuit is a PWM driver that varies the duty cycle to control the amount of current through the motor to ground.
This DTC detects a short to power on the Motor Control A circuit or the Motor Control B circuit.

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

Action Taken When the DTC Sets
^ All clutch activation (slip control) will be disabled.
^ The SERVICE indicator (AWD/4WD) lamp will be latched on for the remainder of the current ignition cycle.

Conditions for Clearing the DTC
^ Current 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. Tests the motor circuit for a current malfunction.
3. Tests Motor Control A for an open or short to voltage.
4. Tests Motor Control B for an open or short to voltage.
5. Tests for continuity across the motor windings.