Transfer Case Shift Control Switch Indicator Lamps Inoperative

Transfer Case Shift Control Switch Indicator Lamps Inoperative - One or More





Test 1-8

Circuit Description
The indicator lamps circuit consist of four individual indicators contained inside the transfer case shift control switch. They are 2HI, 4HI, 41-0 and Neutral. The 2HI, 4HI, and 4LO indicators are contained inside their respective range button. When the ignition in ON, the transfer case shift control module illuminates the indicator 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 after a shift has been requested and will continue 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 indicators. The solid state circuit also receives voltage whenever the headlamp switch is in the parklamp or headlamp position. When the solid state circuit receives voltage from the headlamp switch, the circuit will reduce the voltage supplied to the indicators, dimming the indicators when the headlamps are ON.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step tests the transfer case electrical control of the indicator control 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 ignition 1 voltage circuit for an open or short to ground.