NVG 126-NP4 Transfer Case

DTC C0327

Circuit Description

The transfer case encoder is an analog sensor that returns a signal that represents the physical position of the transfer case sector shaft. The signal represents the mode or position that the transfer case is currently in.

This sensor is made up of the following 3 circuits:
- A 5-volt reference circuit.
- An encoder signal circuit.
- An encoder low reference circuit.

This DTC detects an out of range reading from the encoder signal or a short to voltage on the 5-volt reference circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0327 Encoder Circuit Malfunction.

Conditions for Setting the DTC

The transfer case shift control module has a predefined range in which the encoder feed back should stay within, 0.5-4.5 volts. The DTC sets if the encoder signal feed back falls out of this range.

Action Taken When the DTC Sets

- All motor activity stops.
- The SERVICE AWD indicator remains illuminated for the remainder of the current ignition cycle.

Conditions for Clearing the DTC

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

Diagnostic Aids

Check the mechanical condition of the shift lever detent shaft connected to the motor. If this shaft has too much mechanical play this can cause an under voltage or over voltage from the encoder causing the DTC to set.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2. This step tests the encoder circuit for a current malfunction.
3. This step tests for proper reference voltage at the encoder.
4. This step tests the 5-volt reference encoder circuit for a short to voltage, short to ground, an open or high resistance.
5. After determining that the reference voltage measured in step 4 was correct, step 6 reviews the reading originally measured in step 3 to see if it was higher or lower than what is expected. This step helps determine whether the encoder signal circuit is being pulled high or low.
6. This step tests the encoder signal circuit and the encoder low reference circuit for a short to voltage.
7. This step helps determine a faulty encoder.
8. This step tests the encoder signal circuit for an open or a short to ground.
9. This step tests the encoder low reference circuit for an open or high resistance.