GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2003 🢒 H2 🢒 Driveline/Axle 🢒 Transfer Case - BW 4484 🢒 Transfer Case Shift Control Switch Inoperative

Circuit Description

The range/mode switch circuit consists of the following 5 switches:

    • 4HI
    • 4HI Lock
    • 4LO Lock
    • Neutral
    • Differential Lock

The transfer case shift control module supplies a regulated 5 volts, DC to the switch through the 5 volt regulator circuit. The current travel through the resistor of the currently active switch. The switch then returns current to the transfer case shift control module through the switch signal circuit.

The transfer case shift control module constantly monitors this signal voltage to determine the condition of the mode switch circuit.

When each switch is depressed, the switch will complete a circuit through the respective resistor. The transfer case shift control module continuously monitors the switch input to determine which of the following buttons were selected by the driver:

    • 4HI
    • 4HI Lock
    • 4LO Lock
    • Differential Lock

Test Description

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

  1. Tests the functionality of the mode switch.

    2.

  2. Tests the modules ability to operate the transfer case modes.

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. Start the engine.
  3. Place the transmission into neutral.
  4. Set the park brake.
  5. Observe the mode switch selected parameter on the scan tool while selecting each of the mode positions on the switch.

Does the state change with the selection of any of the mode positions?

Go to Step 5

Go to Step 3

3

Check the switch signal and 5 volt reference circuits for an open, high resistance, short to ground, and short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 4

4

Replace the mode selection switch. Refer to Transfer Case Shift Control Switch Replacement .

Did you complete the repair?

Go to Step 6

--

5

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

Did you complete the repair?

Go to Step 6

--

6
  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