WATER-IN-FUEL INDICATOR
DESCRIPTION
A water-in-fuel indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with the optional diesel engine, this indicator is electronically disabled. This indicator is located above the fuel gauge on the cluster overlay, to the left of the speedometer.
The water-in-fuel indicator consists of a stencil-like cutout of the International Control and Display Symbol icon for Water In Fuel in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. An amber Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the indicator to appear in amber through the translucent outer layer of the overlay when it is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board.
The water-in-fuel indicator is serviced as a unit with the instrument cluster.
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 circuit board 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 Light Emitting Diode (LED) 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 LED will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the water-in-fuel indicator for the following reasons:
- 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 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 electronic water-in-fuel message to the ElectroMechanical Instrument Cluster (EMIC).
For proper diagnosis of the water-in-fuel-sensor, the PCM, the EMIC, 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.