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 five individual lamps contained inside the mode switch assembly. They are 4HI, 4HI Lock, 4LO Lock, Neutral, and Differential Lock. The 4HI, 4HI Lock, 4LO Lock, and Differential Lock, are contained inside their respective mode 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 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

Steps 1-8:

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.