C0327

DTC C0327

CIRCUIT DESCRIPTION
The transfer case shift control module has four encoder channels coming out of it which are all supplied 5 volts. These four channels are P, C, A, and B, each running to a switch located inside the encoder/motor assembly. When a particular encoder channel is active the switch is closed and 5 volts flows through the encoder signal return circuit. If the module wants to request motor position a low side driver pulls the voltage low on the encoder signal return and the corresponding channel circuit indicating motor position.

The transfer case shift control module supplies 5 volts on all the channels, thus as these channels are pulled to ground, the module can interpret the location of the transfer case shift position.

This DTC detects an open, high resistance, or a short to voltage, in the encoder signal return circuit, or an open, high resistance, or short to voltage in the encoder channel circuits.

CONDITIONS FOR RUNNING THE DTC
- Ignition is ON.
- System voltage is 9-18 volts.

CONDITIONS FOR SETTING THE DTC
The transfer case shift control module reads back a high voltage when a low voltage is expected, or low voltage when a high voltage is expected on the encoder channel circuits, or the encoder signal return circuit.

ACTION TAKEN WHEN THE DTC SETS
- All motor activity will stop.
- All the transfer case shift control switch mode indicators will be commanded OFF.
- The SERVICE 4WD indicator will be latched on for the remainder of the current ignition cycle.
- If a new mode is requested while the DTC is present either current or history, the indicator for the mode requested will flash for 15 seconds and then go out.

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 33 consecutive ignition cycles without a fault present.
- History DTCs can be cleared using a scan tool.

TEST DESCRIPTION

Steps 1-2:

Steps 3-12:

The numbers below refer to the step numbers on the diagnostic table.
2. Determines if two or more of the 5 volts encoder signal circuits are shorted together.
3. Checks for proper voltage on the four encoder signal circuits.
4. Tests for a short to voltage, open, or high resistance on the encoder low reference circuit.
5. Determines if the encoder motor is pulling the encoder signal return low.
6. Determines which encoder signal circuits are shorted together.
7. Determines if any of the encoder signal circuits have an open, or high resistance condition.
8. Determines if a binding shift detent lever shaft is causing the DTC.