Light Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the icon to appear
silhouetted against an amber field through the trans-
lucent outer layer of the overlay when the indicator
is illuminated from behind by the LED, which is sol-
dered onto the instrument cluster electronic circuit
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 or the electronic brake
force distribution (EBV) systems are faulty or inoper-
ative. 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)
over the Controller Area Network (CAN) data bus.
The ABS indicator Light Emitting Diode (LED) is
completely controlled by the instrument cluster logic
circuit, and that logic will only allow this indicator to
operate when the instrument cluster detects that the
ignition switch is in the On position. Therefore, the
LED will always be off when the ignition switch is in
any position except On. The LED only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the ABS indicator for the following 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.
The CAB continually monitors the ABS and EBV
circuits and sensors to decide whether the systems
are in good operating condition. The CAB then sends
the proper lamp-on or lamp-off messages to the
instrument cluster. If the CAB sends a lamp-on mes-
sage after the bulb test, it indicates that the CAB
has detected a system malfunction and/or that the
ABS or EBV systems have become inoperative. The
CAB will store a Diagnostic Trouble Code (DTC) for
any malfunction it detects. For proper diagnosis of
the ABS and EBV systems, the CAB, the CAN data
bus, the electronic message inputs to the instrument
cluster, or the instrument cluster circuitry that con-
trols the ABS indicator, a diagnostic scan tool is
required. Refer to the appropriate diagnostic infor-
mation.
ADR INDICATOR
DESCRIPTION
A constant engine speed (ADR) indicator is stan-
dard equipment on all instrument clusters, but is
only
functional
on
vehicles
equipped
with
the
optional ADR switch. The ADR indicator is located
near the lower edge of the instrument cluster, to the
right of the multi-function indicator display. The
ADR indicator consists of the text “ADR” imprinted
within a rectangular cutout 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 text to appear
silhouetted against an amber field through the trans-
lucent outer layer of the overlay when the indicator
is illuminated from behind by the LED, which is sol-
dered onto the instrument cluster electronic circuit
board. The ADR indicator is serviced as a unit with
the instrument cluster.
OPERATION
The constant engine speed (ADR) indicator gives
an indication to the vehicle operator concerning the
operating status of the constant engine speed (ADR)
feature. The ADR indicator is controlled by a transis-
tor on the instrument cluster circuit board based
upon cluster programming and electronic messages
received by the cluster from the Engine Control Mod-
ule (ECM) over the Controller Area Network (CAN)
data bus. The ADR indicator Light Emitting Diode
(LED) is completely controlled by the instrument
cluster logic circuit, and that logic will only allow
this indicator to operate when the instrument cluster
detects that the ignition switch is in the On position.
Therefore, the LED will always be off when the igni-
tion switch is in any position except On. The LED
only illuminates when it is provided a path to ground
by the instrument cluster transistor. The instrument
cluster will turn on the traction control indicator for
the following reasons:
• Constant Engine Speed (ADR) Indicator
Lamp-On Message - Each time the cluster receives
an ADR indicator lamp-on message from the ECM,
the indicator will be illuminated. The indicator is
illuminated when the ADR feature has been acti-
vated with the ADR switch, and is turned off when
the ADR feature is deactivated with the ADR switch.
The ADR indicator will be extinguished if the ADR
feature is turned off because the park brake has been
released or the vehicle is in motion. The ADR indica-
tor will also be extinguished if the service brake
pedal is depressed, but the ADR feature will auto-
matically be restored and the indicator illuminated
when the brake pedal is released. The indicator
8J - 10
INSTRUMENT CLUSTER
VA