Odometer Description; Operation - Jeep Wrangler 2001 Service Manual

TJ
MALFUNCTION INDICATOR LAMP MIL (Continued)
require service. For proper diagnosis of the fuel and
emissions systems, the PCM, the PCI data bus, or
the message inputs to the instrument cluster that
control the MIL, a DRBIII
Refer to the appropriate diagnostic information.
ODOMETER
DESCRIPTION
An odometer and trip odometer are standard
equipment in all instrument clusters. The odometer
and trip odometer information are displayed in a
common electronic Vacuum Fluorescent Display
(VFD), which is centered on the lower edge of the
instrument cluster and visible through a small win-
dow cutout on the instrument cluster overlay. How-
ever, the odometer and trip odometer information are
not displayed simultaneously. The trip odometer
reset switch on the instrument cluster electronic cir-
cuit board toggles the display between odometer and
trip odometer modes by depressing the odometer/trip
odometer switch knob that extends through the lower
edge of the cluster lens, just right of the odometer
VFD. Both the odometer and trip odometer informa-
tion is stored in the instrument cluster memory.
The odometer can display values up to 999,999
kilometers (999,999 miles). The odometer will not roll
over, but will latch at the maximum value. The trip
odometer can display values up to 9999.9 kilometers
(9999.9 miles) before it rolls over to zero. The odom-
eter display does not have a decimal point and will
not show values less than a full unit (kilometer or
mile), the trip odometer display does have a decimal
point and will show tenths of a unit (kilometer or
mile). The unit of measure for the odometer and trip
odometer display is not shown in the VFD. If the
instrument cluster has a speedometer with a primary
scale in kilometers-per-hour, the letters "KM" are
printed on the cluster mask next to the VFD window
to indicate the odometer unit of measure. During
daylight hours (exterior lamps Off) the VFD is illu-
minated at full brightness for clear visibility. At night
(exterior lamps are On) an analog/digital (A/D) con-
verter on the instrument cluster electronic circuit
board converts the analog panel lamps dimmer input
from the left multi-function switch to a digital dim-
ming level signal for controlling the lighting level of
the VFD. However, a "Parade" mode position of the
panel lamps dimmer control ring of the left multi-
function switch control stalk allows the VFD to be
illuminated at full brightness while the exterior
lamps are turned On during daylight hours.
The VFD, the trip odometer switch, and the trip
odometer switch button are serviced as a unit with
the instrument cluster. The rubber trip odometer
2001 JEEP WRANGLER
scan tool is required.
INSTRUMENT CLUSTER
reset knob boot on the outside of the cluster lens is
available for separate service replacement.

OPERATION

The odometer and trip odometer give an indication
to the vehicle operator of the distance the vehicle has
traveled. This gauge is controlled by the instrument
cluster electronic circuitry based upon cluster pro-
gramming and electronic messages received by the
cluster from the Powertrain Control Module (PCM)
over the Programmable Communications Interface
(PCI) data bus. The odometer and trip odometer
information is displayed by the instrument cluster
Vacuum Fluorescent Display (VFD), and the VFD
will display odometer or trip odometer cluster infor-
mation whenever the driver door is opened or the
ignition switch is turned to the On or Start positions.
The instrument cluster circuitry controls the VFD
and provides the following features:
• Odometer/Trip Odometer Display Toggling -
Actuating the trip odometer reset switch momen-
tarily with the VFD illuminated will toggle the dis-
play between the odometer and trip odometer
information. Each time the VFD is illuminated the
display will automatically return to the last mode
previously selected (odometer or trip odometer).
• Trip Odometer Reset - When the trip odome-
ter reset switch is pressed and held for longer than
about two seconds, trip odometer will be reset to 0.0
kilometers (miles). The VFD must be displaying the
trip odometer information in order for the trip odom-
eter 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, either "888888"will be displayed in
the VFD or the VFD will be blank.
• Actuator Test - Each time the cluster is put
through the actuator test, the VFD will scroll the
number "8" from right-to-left across the display, then
illuminate the trip odometer decimal point "." in
order to confirm the functionality of the VFD and the
cluster control 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
8Js - 27