ter. For further diagnosis of the MIL or the instrument cluster circuitry that controls the LED, (Refer to 8 - ELEC-
TRICAL/INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). If the instrument cluster turns on the MIL after the
bulb test, it may indicate that a malfunction has occurred and that the fuel and emissions systems may require
service.
For proper diagnosis of the fuel and emissions systems, the PCM, the CAN data bus, or the electronic message
inputs to the instrument cluster that control the MIL, a diagnostic scan tool is required. Refer to the appropriate
diagnostic information.
ODOMETER
DESCRIPTION
An odometer and trip odometer are standard equip-
ment in all instrument clusters. The odometer, trip
odometer, and engine hours information are displayed
in a common electronic, blue-green Vacuum-Fluores-
cent Display (VFD) unit. This VFD unit is soldered
onto the cluster electronic circuit board and is visible through a window with a smoked clear lens located below the
tachometer in the lower right area of the cluster overlay. The dark lens over the VFD prevents the indicator from
being clearly visible when it is not illuminated.
The odometer, trip odometer, and engine hours information are not displayed simultaneously. The trip odometer
reset switch on the instrument cluster circuit board toggles the display between odometer and trip odometer modes
by depressing the odometer/trip odometer switch button that extends through the lower edge of the cluster lens, just
left of the minor gauge set. When the trip odometer information is displayed, the word “TRIP” is also illuminated in
the lower right corner of the odometer/trip odometer VFD in a blue-green color and at the same lighting level as the
trip odometer information. The engine hours information replaces the selected odometer or trip odometer information
whenever the ignition switch is in the On position and the engine is not running.
The odometer, trip odometer, and engine hours information is stored in the instrument cluster memory. This infor-
mation can be increased when the proper inputs are provided to the instrument cluster, but the information cannot
be decreased. The odometer can display values up to 999,999 kilometers (999,999 miles). The odometer latches at
these values, and will not roll over to zero. The trip odometer can display values up to 999.9 kilometers (999.9
miles) before it rolls over to zero. Engine hours are displayed in the format, “hr9999”. The cluster will accumulate
values up to 9,999 hours before the display rolls over to zero.
The odometer display does not have a decimal point and will not show values less than a full unit (kilometer or
mile), while the trip odometer display does have a decimal point and will show tenths of a unit (kilometer or mile).
The unit of measure (kilometers or miles) for the odometer and trip odometer display is not shown in the VFD. The
unit of measure for the instrument cluster odometer/trip odometer is selected at the time that it is manufactured, and
cannot be changed. The odometer also has a “Rental Car” mode, which will illuminate the odometer information in
the VFD whenever the driver side front door is opened with the ignition switch in the Off or Accessory positions.
During daylight hours (exterior lamps are Off) the odometer VFD is illuminated at full brightness for clear visibility. At
night (exterior lamps are On), the VFD lighting level is adjusted with the other cluster illumination lamps using the
panel lamps dimmer thumbwheel on the headlamp switch. However, a “Parade” mode position of the panel lamps
dimmer thumbwheel allows the VFD to be illuminated at full brightness if the exterior lamps are turned On during
daylight hours.
The odometer/trip odometer VFD, the trip odometer switch, and the trip odometer switch button are serviced as a
unit with the instrument cluster.
OPERATION
The odometer and trip odometer give an indication to the vehicle operator of the distance the vehicle has traveled.
The engine hours give an indication of the cumulative engine-on time. This indicator is controlled by the instrument
cluster circuitry based upon cluster programming and electronic messages received by the cluster from the Power-
train Control Module (PCM) over the Controller Area Network (CAN) data bus.
The odometer, trip odometer and engine hours information is displayed by the instrument cluster odometer/trip
odometer Vacuum Fluorescent Display (VFD). The VFD will display the odometer information whenever any door is
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