• Trip Odometer Reset - When the trip odome-
ter reset switch is pressed and held for longer than
about two seconds, the trip odometer will reset to
000.0 kilometers (miles). The VFD must be display-
ing the trip odometer information in order for the
trip odometer information to be reset.
• Message Failure - If the cluster fails to receive
a distance message during normal operation, it will
hold and display the last data received until the igni-
tion switch is turned to the Off position. If the clus-
ter does not receive a distance message within one
second after the ignition switch is turned to the On
position, it will display the last distance message
stored in the cluster memory. If the cluster is unable
to display distance information due to an error inter-
nal to the cluster, the VFD display will be blank.
• Actuator Test - Each time the cluster is put
through the actuator test, the VFD will display all of
each number (0 through 9) in steps to confirm the
functionality of the VFD and the cluster circuitry.
The PCM continually monitors the vehicle speed
sensor, then sends the proper distance messages to
the instrument cluster. For further diagnosis of the
odometer/trip odometer or the instrument cluster cir-
cuitry that controls these functions, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNO-
SIS AND TESTING). For proper diagnosis of the
vehicle speed sensor, the PCM, the PCI data bus, or
the message inputs to the instrument cluster that
control the odometer/trip odometer, a DRBIII
t scan
tool and the appropriate diagnostic information are
required.
OIL PRESSURE GAUGE
DESCRIPTION
An oil pressure gauge is standard equipment on all
instrument clusters. The oil pressure gauge is located
in the upper right quadrant of the instrument clus-
ter, above the engine coolant temperature gauge. The
oil pressure gauge consists of a movable gauge needle
or pointer controlled by the instrument cluster cir-
cuitry and a fixed 90 degree scale on the gauge dial
face that reads left-to-right either from 0 kg/cm to
8.3 kg/cm, or from 0 psi to 80 psi, depending upon
the market for which the vehicle is manufactured. An
International Control and Display Symbol icon for
“Engine Oil” is located in the center of the gauge dial
face, directly below the 4 kg/cm or 40 psi graduation
of the gauge scale. The oil pressure gauge graphics
are either white and red against a black gauge dial
face (Laredo), or blue-green and red against a
brushed aluminum gauge dial face (Limited), making
them clearly visible within the instrument cluster in
daylight. When illuminated from behind by the panel
lamps dimmer controlled cluster illumination lighting
with the exterior lamps turned On, the white graph-
ics (Laredo) appear blue-green, the blue-green graph-
ics (Limited) still appear blue-green, while the red
graphics for both models still appear red. The orange
gauge needle is internally illuminated. Gauge illumi-
nation is provided by replaceable incandescent bulb
and bulb holder units located on the instrument clus-
ter electronic circuit board. The oil pressure gauge is
serviced as a minor gauge set with the engine coolant
temperature gauge.
OPERATION
The oil pressure gauge gives an indication to the
vehicle operator of the engine oil pressure. This
gauge is controlled by the instrument cluster circuit
board based upon the cluster programming and elec-
tronic messages received by the cluster from the
Powertrain Control Module (PCM) over the Program-
mable Communications Interface (PCI) data bus. The
oil pressure gauge is an air core magnetic unit that
receives battery current on the instrument cluster
electronic circuit board through the fused ignition
switch output (st-run) circuit whenever the ignition
switch is in the On or Start positions. The cluster is
programmed to move the gauge needle back to the
low end of the scale after the ignition switch is
turned to the Off position. The instrument cluster
circuitry controls the gauge needle position and pro-
vides the following features:
• Engine Oil Pressure Low Message - Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is about 0.003
kg/cm or lower (about 6 psi or lower), the gauge
needle is moved to the far left (low) end of the gauge
scale and the check gauges indicator is illuminated.
The gauge needle remains at the low end of the scale
and the check gauges indicator remains illuminated
until the cluster receives a message from the PCM
indicating that the engine oil pressure is about 0.004
kg/cm or higher (about 8 psi or higher), or until the
ignition switch is turned to the Off position, which-
ever occurs first. The cluster will only turn the check
gauges indicator lamp on in response to an engine oil
pressure low message if the engine speed is 300 rpm
or greater.
• Message Failure - If the cluster fails to receive
an engine oil pressure message, it will hold the
gauge needle at the last indication for about twelve
seconds, until a new message is received, or until the
ignition switch is turned to the Off position, which-
ever occurs first.
• Actuator Test - Each time the cluster is put
through the actuator test, the gauge needle will be
swept across the entire gauge scale and back in order
WG
INSTRUMENT CLUSTER
8Js - 19
ODOMETER (Continued)
2001 JEEP GRAND CHEROKEE