GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Yukon XL - 4WD 🢒 Driveline/Axle 🢒 Transfer Case - NVG 263-NP1 (Selectable) 🢒 Transfer Case Shift Control Switch Indicator Inoperative - One or More

Circuit Description

The indicator lamps circuit consist of four individual indicators 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. When the ignition in 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.

A solid state circuit located inside the switch supplies ignition voltage to the indicators. The solid state circuit also receives voltage whenever the headlamp switch is in the parklamp or headlamp position. When the solid state circuit receives voltage from the headlamp switch, the circuit will reduce the voltage supplied to the indicators, dimming the indicators when the headlamps are ON.

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 control circuits.

    2.

  2. This step helps determine module failures.

    3.

  3. This step tests the affected indicator control circuit for an open or high resistance.

    4.

  4. This step tests the ignition 1 voltage circuit for an open or short to ground.

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 ON.

Do all the indicators go ON?

Go to Step 7

Go to Step 3

3

  1. Access the back of the shift control switch.
  2. Using a fused jumper back probe the affected indicator control circuit to ground.

Does the affected indicator go ON?

Go to Step 4

Go to Step 5

4

Test the affected indicator control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 7

5

Test the ignition 3 voltage circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 6

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 causing the symptom to re-occur.

Does the symptom re-occur?

Go to Step 2

System OK