GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Astro - 4WD 🢒 Driveline/Axle 🢒 Transfer Case - NVG 136-NP4 🢒 DTC C0315

Circuit Description

The transfer case encoder motor is a permanent magnet DC motor and gear reduction assembly. The encoder motor is controlled with a pulse width modulated (PWM) circuit within the transfer case shift control module. When voltage is supplied to Motor Control A, Motor Control B supplies a path to ground through the transfer case shift control module and motor ground circuit.

This DTC detects an open in the module ground circuit.

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

Conditions for Setting the DTC

The system test 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 on the motor circuits, its applies voltage through the motor and to module ground.
    • If the system detects a high voltage on the ground circuit, the DTC is logged.

Action Taken When the DTC Sets
    • The SERVICE AWD indicator will be illuminated for the remainder of the current ignition cycle.
    • All clutch activation, slip control will be disabled..

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 100 consecutive ignition cycles without a fault is present.
    • History DTCs can be cleared using a scan tool.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Listen for an audible motor noise when the encoder motor operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. Tests the motor ground circuit for an open.

Step

Action

Yes

No

Schematic Reference: Transfer Case Control Schematics

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. With the scan tool, command the Motor A/B control ON and OFF.

Does the motor encoder 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. Refer to Testing for Continuity 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 reset?

Go to Step 2

System OK