C0327

DTC C0327

Circuit Description
The transfer case shift control module has 4 encoder circuits, and each circuit is supplied 12 volts. These 4 circuits are A, B, C, and P, and each circuit runs to a switch located inside the encoder / motor assembly. When a particular encoder circuit is active, the switch is closed, and the 12 volts are grounded by the switch inside the encoder.

The transfer case shift control module supplies 12 volts on all the circuits. The module can interpret the location of the transfer case shift position when the circuits are grounded.

This DTC detects a fault when it compares the shift sequence / strategy to a chart located in ROM, within the electronic control unit (ECU), within the transfer case shift control module. This is accomplished by the module reading the different combinations of encoder signals being grounded while others remain high depending on what mode or range the transfer case is in.

Conditions for Running the DTC
^ The ignition is ON.
^ The system voltage is 10-16 volts.

Conditions for Setting the DTC
The transfer case shift control module sets the DTC when the encoder signals do not match the chart contained in ROM. This DTC can be set while no shift is requested or while a shift is being performed.

Action Taken When the DTC Sets
^ All motor activity will stop.
^ All accessory mode indicators will be commanded OFF.
^ The SERVICE 4WD indicator will be on until the fault is corrected.
^ If a new mode is requested by the driver when the DTC is either current or present in DTC history, the transfer case control module will only allow a shift to 2WD mode. The transfer case control module will not allow further mode changes.

Conditions for Clearing the DTC
^ The DTC will set as both current and history.
^ Use a scan tool in order to clear a history DTC.
^ A scan tool must be used to clear a DTC.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if module is providing correct output voltage on the encoder signal circuits.
3. This, step determines if the four encoder signal circuits are shorted together.
4. This; step determines if any of the four encoder signal circuits are shorted to ground, or have high resistance.

Steps 1 - 7:

DTC C0327