GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2006 🢒 H2 🢒 DTC 🢒 DTC C0329

Circuit Description

The transfer case shift control module has 4 encoder channels coming out of it which are all supplied 5 volts. These 4 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. As these channels are pulled to ground, the module can interpret the location of the transfer case shift position.

This DTC detects a short to ground in the encoder signal return circuit, or a short to ground in the encoder channel circuits.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0329 Encoder Signal Circuit Low

Conditions for Running the DTC
    • The ignition is ON.
    • The system voltage is 9-18 volts.

Conditions for Setting the DTC

The transfer case shift control module can command the low side driver on the encoder signal return circuit not to pull the signal low. The module can then read the voltage on each of the encoder channel circuits. If the voltage is low a short to ground is indicated and the DTC is logged.

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 commanded ON, and an active DTC set, when a shift is requested.
    • If a shift is not being requested the DTC will go to history.
    • 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

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

  1. This step determines if one or more of the encoder channel circuits are shorted to ground.

    2.

  2. This step checks with a digital multimeter (DMM) for a short to ground on any of the 4 encoder channel circuits.

    3.

  3. This step checks the encoder sign return circuit for a short to ground.

    4.

  4. This step determines if a faulty transfer case shift control module is causing the DTC to set.

    5.

  5. This step determines if the encoder motor is causing the DTC to set.

Step

Action

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 at the transfer case.
  4. Turn the ignition ON, with the engine OFF.
  5. Install a scan tool.
  6. Monitor the encoder channels P, B, A, and C on the scan tool.

Do any of the encoder channels indicate OFF?

Go to Step 3

Go to Step 4

3

Test the encoder channel circuit that is indicating OFF on the scan tool for a short to ground. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

4

With the ignition in the OFF position, test the encoder low reference circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 9

Go to Step 5

5

  1. Turn the ignition ON with the engine OFF.
  2. With the transfer case connector still disconnected, use the scan tool to clear DTCs.

Does DTC C0329 reset?

Go to Step 8

Go to Step 6

6

  1. Turn the ignition OFF.
  2. Connect the transfer case connector.
  3. Turn the ignition ON, with the engine OFF.
  4. With the transfer case shift control switch, command the transfer case through all of the modes.
  5. Using a scan tool, check DTCs.

Does DTC C0329 set?

Go to Step 7

Go to Testing for Electrical Intermittents

7

Replace the encoder motor. Refer to Transfer Case Motor/Encoder Replacement .

Did you complete the repair?

Go to Step 9

--

8

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 9

--

9
  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