Commander 4WD V8-4.7L Flex Fuel (2009)
Water In Fuel Indicator: Description and Operation
Water In Fuel Indicator - Operation
OPERATION
The water-in-fuel indicator gives an indication to the vehicle operator when there is excessive water detected in the diesel fuel. This indicator is
controlled by the instrument cluster logic circuit based upon cluster programming and electronic messages received over the Controller Area Network
(CAN) data bus from the Powertrain Control Module (PCM).
The water-in-fuel 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 water-in-fuel indication will always be OFF when the ignition switch is in any
position except ON or START. The instrument cluster will turn ON the water-in-fuel indicator for the following reasons:
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Water-In-Fuel Indicator Lamp-On Message - Each time the cluster receives an electronic water-in-fuel indicator lamp-ON message from the
PCM indicating there is excessive water in the diesel fuel system, the water-in-fuel indicator will be illuminated. The indicator remains illuminated
for about five seconds, until the cluster arbitrator logic determines that another display request has priority, until the cluster receives a lamp-OFF
message from the PCM, or until the ignition switch is turned to the OFF position, whichever occurs first.
The PCM continually monitors the water-in-fuel sensor to determine whether there is excessive water in the diesel fuel system. The PCM 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 water-in-fuel-sensor, the PCM, the CCN, the CAN data bus, or the electronic communication related to water-in-fuel
indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.
