Transfer Case Shift Control Switch Indicator Always on - Two or More

Transfer Case Shift Control Switch Indicator Always On - Two or More




Circuit Description
The indicator lamps circuit consist of five individual lamps contained inside the mode range switch assembly. They are AUTO 4WD, 2HI, 4Hi, 4LO and Neutral. The AUTO 4WD, 2HI, 4HI, and 4LO lamps are contained inside their respective range button. When the ignition is 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 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. Tests the transfer case electrical control of the lamp circuits.
3. Helps determine a short to ground in the suspect lamp circuits.
4. Test the suspect lamp circuits for a short to ground.
5. Repair short to ground in the suspect lamp circuit.