Durango 2WD V6-3.7L (2009)
Fog/Driving Lamp Indicator: Description and Operation
Fog Lamp Indicator - Operation
OPERATION
The fog lamp indicator gives an indication to the vehicle operator whenever the optional fog lamps are illuminated. This indicator is controlled by the
instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Front Control Module (FCM)
over the Controller Area Network (CAN) data bus.
The fog lamp indicator is completely controlled by the instrument cluster logic circuit. This logic only allows the indicator to operate whenever the
instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the indicator is always 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 turns on the fog lamp indicator for the following reasons:
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Fog Indicator Lamp-On Message - Each time the cluster receives an electronic fog indicator lamp-on message from the FCM indicating the fog
lamp relay is energized, the fog lamp indicator illuminates. The indicator remains illuminated until the cluster receives a lamp-OFF message from
the FCM, until the ignition switch is turned to the OFF position or until the exterior lamp load shedding (battery saver) timed interval expires,
whichever occurs first.
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Actuator Test - Each time the cluster is put through the actuator test, the fog lamp indicator turns on, then off again during the VFD portion of the
test to confirm the functionality of the VFD and the cluster control circuitry.
The FCM continually monitors electronic exterior lighting switch status messages from the instrument cluster, also known as the Cab Compartment Node
(CCN) to determine the appropriate outputs to the fog lamp relay. The FCM activates or deactivates the fog lamp relay then sends the proper lamp-on or
lamp-off message back to the CCN. For further diagnosis of the fog lamp indicator or the instrument cluster circuitry that controls the indicator, See:
Instrument Cluster / Carrier/Testing and Inspection.
Use a diagnostic scan tool for proper diagnosis of the fog lamp system, the FCM, the CCN, the CAN data bus or the electronic communication related to
fog lamp indicator operation. Refer to the appropriate diagnostic information.