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8Js - 20
INSTRUMENT CLUSTER
CRUISE INDICATOR
DESCRIPTION
A cruise indicator is standard equipment on all
instrument clusters, but is only functional on vehi-
cles equipped with the optional speed control system.
The cruise indicator is located near the upper edge of
the instrument cluster overlay, in the upper left
quadrant of the cluster. The cruise indicator consists
of a stencil-like cutout of the word "CRUISE" in the
opaque layer of the instrument cluster overlay. The
dark outer layer of the overlay prevents the indicator
from being clearly visible when the it is not illumi-
nated. A green lens behind the cutout in the opaque
layer of the overlay causes the "CRUISE" text to
appear in green through the translucent outer layer
of the overlay when it is illuminated from behind by
a Light Emitting Diode (LED) soldered onto the
instrument cluster electronic circuit board. When the
exterior lighting is turned On, the illumination inten-
sity of the cruise indicator is one-step dimmable,
which is adjusted using the panel lamps dimmer con-
trol ring on the left multi-function switch control
stalk. The cruise indicator is serviced as a unit with
the instrument cluster.
OPERATION
The cruise indicator gives an indication to the vehi-
cle operator when the speed control system is turned
On, regardless of whether the speed control is
engaged. This indicator is controlled by a transistor
on the instrument cluster electronic circuit board
based upon the cluster programming and electronic
messages received by the cluster from the Powertrain
Control Module (PCM) over the Programmable Com-
munications Interface (PCI) data bus. The cruise
indicator Light Emitting Diode (LED) receives bat-
tery current on the instrument cluster electronic cir-
cuit board through the fused ignition switch output
(run-start) circuit whenever the ignition switch is in
the On or Start positions; therefore, the indicator will
always be off when the ignition switch is in any posi-
tion except On or Start. The LED only illuminates
when it is provided with a path to ground by the
instrument cluster transistor. The instrument cluster
will turn on the cruise indicator for the following rea-
sons:
• Cruise Lamp-On Message - Each time the
cluster receives a cruise lamp-on message from the
PCM indicating the speed control system has been
turned On, the cruise indicator is illuminated. The
indicator remains illuminated until the cluster
receives a cruise lamp-off message from the PCM or
until the ignition switch is turned to the Off position,
whichever occurs first.
2001 JEEP WRANGLER
• Actuator Test - Each time the cluster is put
through the actuator test, the cruise indicator will be
turned on, then off again during the bulb check por-
tion of the test in order to confirm the functionality
of the LED and the cluster control circuitry.
The PCM continually monitors the speed control
switches to determine the proper outputs to the
speed control servo. The PCM then sends the proper
cruise indicator lamp-on and lamp-off messages to
the instrument cluster. For further diagnosis of the
cruise indicator or the instrument cluster circuitry
that controls the indicator, (Refer to 8 - ELECTRI-
CAL/INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). For proper diagnosis of the speed control
system, the PCM, the PCI data bus, or the message
inputs to the instrument cluster that control the
cruise indicator, a DRBIII
Refer to the appropriate diagnostic information.
ENGINE TEMPERATURE
GAUGE
DESCRIPTION
An engine coolant temperature gauge is standard
equipment on all instrument clusters. The engine
coolant temperature gauge is located in the lower
right quadrant of the instrument cluster, below the
oil pressure gauge. The engine coolant temperature
gauge consists of a movable gauge needle or pointer
controlled by the instrument cluster electronic cir-
cuitry and a fixed 90 degree scale on the cluster over-
lay that reads left-to-right from 40° C (or 100° F) to
125° C (or 260° F). An International Control and Dis-
play Symbol icon for "Engine Coolant Temperature"
is located on the cluster overlay, in the center of the
gauge directly above the hub of the gauge needle.
The engine coolant temperature gauge graphics are
white and blue against a black field except for a sin-
gle red graduation at the high end of the gauge scale,
making them clearly visible within the instrument
cluster in daylight. When illuminated from behind by
the panel lamps dimmer controlled cluster illumina-
tion lighting with the exterior lamps turned On, the
white graphics appear white, the blue graphics
appear blue, and the red graphics appear red. The
orange gauge needle is internally illuminated. Gauge
illumination is provided by replaceable incandescent
bulb and bulb holder units located on the instrument
cluster electronic circuit board. The engine coolant
temperature gauge is serviced as a unit with the
instrument cluster.
TJ
scan tool is required.
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