GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 GMC C Sierra - 2WD 🢒 Driveline/Axle 🢒 Transfer Case - NVG 263-NP1 (Selectable) 🢒 Transfer Case Shift Control Switch Indicator Always On - Two or More

Circuit Description

The indicator circuits consist of four individual lamps contained inside the transfer case shift control switch. They are 2HI, 4HI, 4LO and NEUTRAL. The 2HI, 4HI, and 4LO indicators are contained inside their respective range button. The NEUTRAL indicator is located on the front panel of the switch. When the ignition is ON, the transfer case shift control module illuminates the indicator that corresponds to the current ATC gear position by providing a ground through a current limiting driver. The transfer case shift control module flashes each indicator after a shift has been requested, and will continue to flash until the transfer case shift control module can complete the shift.

Test Description

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

  1. This step tests the transfer case electrical control of the indicator circuits.

    2.

  2. This step helps determine a short to ground in the suspect indicator control circuits.

    3.

  3. This step tests the suspect indicator control circuits for a short to ground.

    4.

  4. Repair short to ground in the suspect indicator control circuit.

Step

Action

Yes

No

Schematic Reference: Transfer Case Control Schematics

1

Was the Transfer Case Diagnostic System Check performed?

Go to Step 2

Go to Diagnostic System Check - Transfer Case

2

  1. Turn ON the ignition, with the engine OFF.
  2. Install a scan tool.
  3. Use the scan tool in order to command all the indicators OFF.

Do all the indicators go OFF?

Go to Step 7

Go to Step 3

3

  1. Use the scan tool in order to determine which mode the transfer case is in.
  2. Use this information to determine which indicator control circuit is at fault.
  3. Disconnect the shift control switch.
  4. Test the suspect indicator control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the suspect circuits shorted to ground?

Go to Step 4

Go to Step 6

4

  1. Disconnect the transfer case shift control module.
  2. Test the suspect indicator control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the suspect circuits shorted to ground?

Go to Step 5

Go to Step 7

5

Repair the short to ground in the suspect indicator control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

--

6

Replace the shift control switch. Refer to Transfer Case Shift Control Switch Replacement .

Did you complete the replacement?

Go to Step 8

--

7

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

Did you complete the replacement?

Go to Step 8

--

8
  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the conditions for allowing the symptom to occur.

Does the symptom occur?

Go to Step 2

System OK