Transfer Case Shift Control Switch Indicator Inoperative - One or More

Transfer Case Shift Control Switch Indicator Inoperative - One or More

Test 1-8:

Circuit Description
The indicator lamps circuit consist of five individual lamps contained inside the mode/range switch assembly. They are AUT0 4WD, 2HI, 4HI, 4LO and NEUTRAL. The AUT04WD, 2HI, 4HI, and 4LO lamps are contained inside their respective range button. When the ignition in ON, the transfer case shift control module illuminates the indicator lamp 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 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, it reduces the voltage that it supplies to the indicator lamps, dimming the lamps when the headlamps are ON.

Test Description
The numbers 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 lamp circuit for an open or high resistance.
5. This step tests the lamp feed circuit for an open or short to Ground.