For 1990-2009 cars

### 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 read only memory (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.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0327 Encoder Circuit Malfunction

### 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.

### Diagnostic Aids

• | Check the inline connector C105 for proper connection, bent pins, damage, or corrosion. Refer to Harness Routing Views and Delphi Connectors .

• | Check the transfer case shift control module connectors C1 and C2 for proper connection and bent or corroded pins or terminals. Refer to Repairing Connector Terminals .

• | Check for water leaks at doors and bulkhead areas. Refer to Waterleak Test Preparation .

### Test Description

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

1. This step determines if the module is providing correct output voltage on the encoder signal circuits.

2. This step determines if the 4 encoder signal circuits are shorted together.

3. This step determines if any of the 4 encoder signal circuits are shorted to ground, or have high resistance.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Transfer Case Control Schematics Connector End View Reference: Transfer Case Control Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Set the parking brake.
2. Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle .
3. Disconnect the connector C3 at the transfer case encoder motor.
4. Turn ON the ignition, with the engine OFF.
5. Using a DMM at the encoder motor, test channel encoder signal circuits A, B, C, and P for proper voltage.

Is the voltage within the specified range?

10-16 V

Go to Step 3

Go to Step 4

3 |

1. Disconnect the connector C2 at the transfer case shift control module.
2. Using a DMM, test the channel encoder signal circuits A, B, C, and P for being shorted together. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 7

Go to Step 5

4 | Using a DMM, test the channel encoder signal circuits A, B, C, and P for a short to ground, an open, or a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 6
5 | Replace the encoder motor. Refer to Transfer Case Encoder Motor Replacement . Did you complete the repair? | -- | Go to Step 7 | --
6 | Replace the transfer case shift control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the repair? | -- | Go to Step 7 | --
7 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC set?

--

Go to Step 1

System OK