GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2005 🢒 Yukon XL - 2WD 🢒 Driveline/Axle 🢒 Transfer Case - BW 4482-NR4 🢒 Transfer Case Shift Control Switch Indicator Always On - Two or More

Circuit Description

The indicator lamps circuit consist of the following 3 individual lamps contained inside the mode/range switch assembly:

    • 4LO
    • All wheel drive (AWD)
    • Neutral

The following lamps are contained inside their respective mode button:

    • AWD
    • 4LO

When the ignition in ON, the transfer case shift control module illuminates the indicator that corresponds to the current gear position by providing a ground through a current limiting driver.

The transfer case shift control module flashes each indicator lamp after a shift has been requested and continues 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 lamps. The solid state circuit also receives voltage when the headlamp switch is in the parklamp or headlamp position. When the solid state circuit receives voltage from the headlamp switch, the switch reduces the voltage supplied to the indicator lamps, dimming the lamps when the headlamps are ON.

Test Description

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

  1. This step determines if the module can command the indicators ON.

    2.

  2. This step determines if the indicator or wiring is at fault.

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 - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

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 indicator lamps OFF.

Do all the lamps go OFF?

Go to Step 7

Go to Step 3

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

Is the suspect circuit shorted to ground?

Go to Step 4

Go to Step 6

4
  1. Disconnect the transfer case shift control module.
  2. Test the suspect lamp circuits for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the suspect circuit shorted to ground?

Go to Step 5

Go to Step 7

5

Repair short to ground in the suspect lamp 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 mode switch. Refer to Transfer Case Shift Control Switch Replacement .

Is the repair complete?

Go to Step 8

--

7

Replace the transfer case shift control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Is the repair complete?

Go to Step 8

--

8
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle in order to determine if the symptom has been corrected.

Is the symptom still present?

Go to Step 2

System OK