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DR
INSTRUMENT CLUSTER (Continued)
NOTE: Certain indicators in this instrument cluster
are automatically configured. This feature allows
those indicators to be activated or deactivated for
compatibility with certain optional equipment. If the
problem being diagnosed involves improper illumi-
nation of the cruise indicator, the electronic throttle
control indicator, the overdrive-off indicator, the
service four-wheel drive indicator, the transmission
overtemp indicator, the upshift indicator, the secu-
rity indicator or the gear selector indicator, discon-
nect and isolate the battery negative cable. After
about five minutes, reconnect the battery negative
cable and turn the ignition switch to the On posi-
tion. The instrument cluster should automatically
relearn the equipment in the vehicle and properly
configure the configurable indicators accordingly.
ABS INDICATOR
DESCRIPTION
An Antilock Brake System (ABS) indicator is stan-
dard equipment on all instrument clusters. However,
the instrument cluster can be programmed to disable
this indicator on vehicles that are not equipped with
the ABS or Rear Wheel Anti-Lock (RWAL) brake sys-
tems, which are not available in some markets. On
vehicles equipped with a gasoline engine, the ABS
indicator is located near the lower edge of the instru-
ment cluster, between the tachometer and the speed-
ometer. On vehicles equipped with a diesel engine,
the ABS indicator is located on the right side of the
instrument cluster, to the right of the engine temper-
ature gauge. The ABS indicator consists of a stencil-
like cutout of the International Control and Display
Symbol icon for "Failure of Anti-lock Braking Sys-
tem" 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 icon to appear in amber through the
translucent outer layer of the overlay when the indi-
cator is illuminated from behind by the LED, which
is soldered onto the instrument cluster electronic cir-
cuit board. The ABS indicator is serviced as a unit
with the instrument cluster.
OPERATION
The ABS indicator gives an indication to the vehi-
cle operator when the ABS system is faulty or inop-
erative. This indicator is controlled by a transistor on
the instrument cluster circuit board based upon clus-
ter programming and electronic messages received by
the cluster from the Controller Antilock Brake (CAB)
INSTRUMENT CLUSTER
over the Programmable Communications Interface
(PCI) data bus. The ABS indicator Light Emitting
Diode (LED) is completely controlled by the instru-
ment 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 ABS indicator for the follow-
ing reasons:
• Bulb Test - Each time the ignition switch is
turned to the On position the ABS indicator is illu-
minated by the cluster for about two seconds as a
bulb test.
• ABS Lamp-On Message - Each time the clus-
ter receives a lamp-on message from the CAB, the
ABS indicator will be illuminated. The indicator
remains illuminated until the cluster receives a
lamp-off message from the CAB, or until the ignition
switch is turned to the Off position, whichever occurs
first.
• Communication Error - If the cluster receives
no lamp-on or lamp-off messages from the CAB for
three consecutive seconds, the ABS indicator is illu-
minated. The indicator remains illuminated until the
cluster receives a valid message from the CAB, or
until the ignition switch is turned to the Off position,
whichever occurs first.
• Actuator Test - Each time the instrument clus-
ter is put through the actuator test, the ABS indica-
tor will be turned on, then off again during the bulb
check portion of the test to confirm the functionality
of the LED and the cluster control circuitry.
• ABS Diagnostic Test - The ABS indicator is
blinked on and off by lamp-on and lamp-off messages
from the CAB during the performance of the ABS
diagnostic tests.
The CAB continually monitors the ABS circuits
and sensors to decide whether the system is in good
operating condition. The CAB then sends the proper
lamp-on or lamp-off messages to the instrument clus-
ter. If the CAB sends a lamp-on message after the
bulb test, it indicates that the CAB has detected a
system malfunction and/or that the ABS system has
become inoperative. The CAB will store a Diagnostic
Trouble Code (DTC) for any malfunction it detects.
Each time the ABS indicator fails to light due to an
open or short in the cluster ABS indicator circuit, the
cluster sends a message notifying the CAB of the
condition, then the instrument cluster and the CAB
will each store a DTC. For proper diagnosis of the
antilock brake system, the CAB, the PCI data bus, or
the electronic message inputs to the instrument clus-
8J - 17
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