4WD Neutral Indicator - Operation

4WD NEUTRAL INDICATOR

The 4WD neutral indicator gives an indication to the vehicle operator when the electronic transfer case has been shifted into the 4WD neutral mode. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Final Drive Control Module (FDCM) over the Controller Area Network (CAN) data bus.

The 4WD neutral indicator function of the reconfigurable dot matrix Organic Light Emitting Diode (OLED) display unit 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 OLED 4WD neutral indication will always be OFF when the ignition switch is in any position except ON or START. The instrument cluster will turn ON the 4WD neutral indicator for the following reasons:

- 4WD Neutral Indicator Lamp-On Message - Each time the cluster receives an electronic 4WD neutral indicator lamp-ON message from the FDCM, the indicator will be illuminated. The indicator remains illuminated for about five seconds, until the cluster receives a lamp-OFF message from the FDCM, until the cluster arbitrator logic determines that another display request has priority, or until the ignition switch is turned to the OFF position, whichever occurs first.

The FDCM continually monitors the electronic transfer case through the transfer case shift motor/mode sensor assembly to determine when the 4WD neutral mode is engaged. The FDCM then sends the proper lamp-ON or lamp-OFF message to the instrument cluster, also known as the Cab Compartment Node (CCN).

For proper diagnosis of the transfer case shift motor/mode sensor, the FDCM, the CCN, the CAN data bus or the electronic communication related to 4WD neutral indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.