GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Yukon XL - 2WD 🢒 Driveline/Axle 🢒 Transfer Case - NVG 263-NP1 (Selectable) 🢒 Transfer Case Shift Control Switch Inoperative

Circuit Description

The transfer case shift control switch circuit consists of 3 normally open switches. The transfer case shift control module supplies a regulated 8 volts DC to the switch through the 8 volt-reference circuit. The current travels through a 9.09 K ohms resistor located inside the switch. Then switch returns current to the transfer case shift control module through the 4WD switch signal circuit.

The transfer case shift control module constantly monitors this signal voltage to determine the condition of the shift control switch circuit. The transfer case shift control module will set this DTC If any of the following conditions exist:

    • None of the buttons are pressed, and the transfer case shift control module detects a voltage level outside the possible range (approximately -0.5 to +1.0 volts) for more than 5 minutes
    • A button is held down, or a button is stuck in the down position for a period more than 5 minutes

Each switch will complete a circuit through that switch's own specific resistor, when depressed. The transfer case shift control module continuously monitors the switch input to determine if the following button selections are made by the driver:

    • 4HI
    • 2HI
    • 4LO

Neutral may be obtained if the following conditions are met:

    • The engine is running.
    • The automatic transmission is in neutral, or the clutch pedal is depressed on a manual transmission application
    • The vehicle speed is below 5 km/h (3 mph).
    • The transfer case is in the 2HI mode.

Once these conditions have been met, press and hold both the 2HI and 4LO buttons for 10 seconds in order to shift the transfer case into neutral. The red neutral indicator lamp will illuminate.

Test Description

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

  1. This steps tests the functionality of the transfer case shift control switch buttons.

    2.

  2. This step tests the modules ability to operate the transfer case modes.

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

Important: NEUTRAL range will only be obtained by pressing and holding both the 2 HI and the 4 LO buttons simultaneously for 10 seconds. Refer to the Circuit Description.

  1. Install a scan tool.
  2. Start the engine.
  3. Place the transmission into neutral, or depress the clutch pedal on manual transmissions.
  4. Set the park brake.
  5. Observe Commanded Mode Indicator states on the scan tool while depressing each of the shift control switch buttons.

Does the state change with the press of any of the shift control switch buttons?

Go to Step 4

Go to Step 3

3

With a scan tool, command through all Commanded Mode Indicator states.

Does the Mode Indicator state change?

Go to Step 4

Go to Step 5

4

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

Did you complete the replacement?

Go to Step 6

--

5

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

Did you complete the replacement?

Go to Step 6

--

6
  1. Use the scan tool in order to clear any DTCs .
  2. Operate the vehicle within the conditions for allowing the symptom to re-occur.

Does the symptom re-occur?

Go to Step 2

System OK