OPERATION

The off road indicator gives an indication to the vehicle operator when the four-wheel drive transfer case is in the 4WD Lock position. This indicator is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster over the Controller Area Network (CAN) data bus.

The off road indicator is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the indicator will always be OFF when the ignition switch is in any position except ON or START. The indicator only illuminates when it is energized by the instrument cluster logic circuit. The instrument cluster will turn ON the off road indicator for the following reasons:

• Off Road Indicator Lamp-On Message - Each time the cluster receives an electronic off road indicator lamp-ON message over the CAN bus indicating the 4WD Lock position of the transfer case has been selected, the off road indicator is illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message over the CAN bus, or until the ignition switch is turned to the OFF position, whichever occurs first.
• Actuator Test - Each time the cluster is put through the actuator test, the off road indicator will be turned ON, then OFF again during the Vacuum Fluorescent Display (VFD) portion of the test in order to confirm the functionality of the VFD and the cluster control circuitry.

The ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) continually monitors the CAN bus to determine the transfer case shifter position and when the off road indicator should be activated or deactivated.

For proper diagnosis of the EMIC, the CAN data bus or the electronic communication related to off road indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.