C0309

Circuit Description
The transfer case encoder motor is a permanent magnet D.C. 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 A) circuit that supplies voltage to the motor through CKT 1552. The Motor B circuit (CKT 1553) 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 circuits 1552 and 1553.

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 circuits 1552 or 1553 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.
- History DTC
- Once 100 consecutive ignition cycles without a fault present.
- A scan tool CLEAR CODES command.

Test Description
The number(s) below refer to the step number(s) on the diagnostic table:
2. This step determines if there is a short to voltage on circuit 1552.





DTC C0309 Motor A/B Circuit High