Transfer Case Shift Control Switch Indicator Inoperative - One or More
Transfer Case Shift Control Switch Indicator Inoperative - One or More
Circuit Description
The indicator lamps circuit consist of the following 5 individual lamps contained inside the mode/range switch assembly:
* 4HI
* 4HI Lock
* 4LO Lock
* Differential Lock
* Neutral
The following lamps are contained inside the respective mode button for each lamp:
* 4HI
* 4HI Lock
* 4LO Lock
* Differential Lock
When the ignition is ON, the transfer case shift control module illuminates the indicator lamp that corresponds to the current automatic transfer case (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 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 lamps. 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 it will reduce the voltage that it supplies 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.
2. This step determines if the module can command the indicators ON.
3. This step determines if the indicator or wiring is at fault.
4. This step tests the lamp feed circuit for an open or high resistance.
5. This step tests the LED dimming circuit for an open or short to ground.
