The indicator lamps circuit consist of 5 individual lamps contained inside the mode/range switch assembly. The following lamps are contained inside the respective range button:

Each time the ignition is cycled, all 5 mode indicators light simultaneously as an indicator check, to ensure proper operation of the indicators. When the ignition is ON, the transfer case shift control module illuminates the indicator lamp that corresponds to the current transfer case 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 completes 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 circuit reduces the voltage that is supplied to the indicator lamps, dimming the lamps when the headlamps are ON.

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

2. This step tests the transfer case electrical control of the lamp circuits.

3. This step helps determine module failures.

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

5. This step tests the LED dimming supply circuit for an open or short to ground.