GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 4WD - RHD 🢒 Driveline/Axle 🢒 Transfer Case - NVG 236-NP8 🢒 DTC C0315

Circuit Description

The transfer case motor is a bi-directional, permanent magnet, DC motor. When energized, the motor through a series of gears, rotates a shaft which moves the mode, and the range forks to shift the transfer case. The transfer case shifts between 4H, AUTO 4WD, 2H, N, and 4L ranges. The motor becomes energized through motor control A, or through motor control B. The ground is provided by the opposing motor control circuit, and then grounded through the transfer case shift control module ground circuit.

This DTC detects an open or a short to voltage in the motor ground circuit.

Conditions for Running the DTC
    • The ignition is ON.
    • System voltage is 9-16 volts.

Conditions for Setting the DTC

The system tests the motor circuits.

    • First, the system checks for unwanted voltage.
    • Then, the system supplies voltage on each of the motor circuits and reads the voltage back on the other circuit.
    • After the system checks for opens and shorts to voltage on the motor circuits, its applies voltage through the motor and back to the module to ground.
    • If the system detects a high voltage on the ground circuit, the DTC is logged.

Action Taken When the DTC Sets
    • The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
    • All shifting is disabled.

Conditions for Clearing the DTC
    • The transfer case shift control module clears the DTC if the condition for setting the DTC does not exist.
    • A history DTC clears after 100 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 listens for an audible motor noise when the encoder motor operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. This step tests the motor ground circuit for an open.

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 - Transfer Case?

Go to Step 2

Go to Diagnostic System Check - Transfer Case

2

  1. Install a scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. Using a scan tool, command the motor A/B control ON and OFF.

Does the encoder motor turn ON and OFF?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn the ignition OFF.
  2. Disconnect the transfer case shift control module.
  3. Test the motor ground circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 5

Go to Step 4

4

Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement .

Did you complete the repair?

Go to Step 5

--

5
  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 2

System OK