Dodge Ram Truck 1500-2500-3500. Manual — part 389

INSTALLATION

WARNING: To avoid personal injury or death, on vehicles equipped with airbags, disable the supplemental
restraint system before attempting any steering wheel, steering column, airbag, seat belt tensioner, impact
sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative
(ground) cable, then wait two minutes for the system capacitor to discharge before performing further diag-
nosis or service. This is the only sure way to disable the supplemental restraint system. Failure to take the
proper precautions could result in accidental airbag deployment.

1. Position the instrument cluster close enough to the

instrument panel to reconnect the three instrument
panel wire harness connectors (1) to the connector
receptacles on the back of the cluster housing (2).

2. Position the instrument cluster into the instrument

panel (4).

3. Install and tighten the four screws (3) that secure

the instrument cluster to the instrument panel struc-
tural support. Tighten the screws to 4 N·m (31 in.
lbs.).

4. Reinstall the cluster bezel onto the instrument

panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
CLUSTER BEZEL - INSTALLATION).

5. Reconnect the battery negative cable.

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 a
problem is noted that involves improper illumination of the cruise indicator, the electronic throttle control
indicator, the service four-wheel drive indicator, the tow/haul indicator, the transmission overtemp indicator,
the upshift indicator, the security indicator or the gear selector indicator, disconnect and isolate the battery
negative cable. After about five minutes, reconnect the battery negative cable and turn the ignition switch to
the On position. The instrument cluster should automatically relearn the equipment in the vehicle and prop-
erly configure the configurable indicators accordingly.

ABS INDICATOR

DESCRIPTION

An Antilock Brake System (ABS) indicator is standard
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 systems, 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 instrument cluster,
between the tachometer and the speedometer. 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 temperature gauge.

The ABS indicator consists of a stencil-like cutout of the International Control and Display Symbol icon for “Failure
of Anti-lock Braking System” in the opaque layer of the instrument cluster overlay. The dark outer layer of the over-
lay 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 indicator is illuminated from behind by the LED, which is soldered onto the
instrument cluster electronic circuit board. The ABS indicator is serviced as a unit with the instrument cluster.

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OPERATION

The ABS indicator gives an indication to the vehicle operator when the ABS system is faulty or inoperative. This
indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and
electronic messages received by the cluster from the Controller Antilock Brake (CAB) over the Programmable Com-
munications Interface (PCI) 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 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 following reasons:

•

Bulb Test - Each time the ignition switch is turned to the On position the ABS indicator is illuminated for about
four seconds as a bulb test. The entire bulb test is a function of the CAB.

•

ABS Lamp-On Message - Each time the cluster receives a lamp-on message from the CAB, the ABS indi-
cator 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 five con-
secutive message cycles, the ABS indicator is illuminated. 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 cluster is put through the actuator test, the ABS indicator 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 con-
dition. The CAB then sends the proper lamp-on or lamp-off messages to the instrument cluster. 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 cluster that control the ABS indicator, a diagnostic scan tool is required. Refer to the appropriate
diagnostic information.

AIRBAG INDICATOR

DESCRIPTION

An airbag indicator is standard equipment on all
instrument clusters. However, the instrument cluster
can be programmed to disable this indicator on vehi-
cles that are not equipped with the airbag system,
which is not available in some markets. The airbag indicator is located near the upper edge of the instrument clus-
ter, between the tachometer and the speedometer.

The airbag indicator consists of a stencil-like cutout of the words “AIR BAG” 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. A red Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the “AIR
BAG” text to appear in red through the translucent outer layer of the overlay when the indicator is illuminated from
behind by the LED, which is soldered onto the instrument cluster electronic circuit board. The airbag indicator is
serviced as a unit with the instrument cluster.

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OPERATION

The airbag indicator gives an indication to the vehicle operator when the airbag system is faulty or inoperative. The
airbag indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming
and electronic messages received by the cluster from the Airbag Control Module (ACM) over the Programmable
Communications Interface (PCI) data bus.

The airbag 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 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 airbag indicator for the following reasons:

•

Bulb Test - Each time the ignition switch is turned to the On position the airbag indicator is illuminated for
about six seconds. The entire bulb test is a function of the ACM.

•

ACM Lamp-On Message - Each time the cluster receives a lamp-on message from the ACM, the airbag indi-
cator will be illuminated. The indicator remains illuminated for about twelve seconds or until the cluster
receives a lamp-off message from the ACM, whichever is longer.

•

Communication Error - If the cluster receives no airbag messages for three consecutive seconds, the airbag
indicator is illuminated. The indicator remains illuminated until the cluster receives a single lamp-off message
from the ACM.

•

Actuator Test - Each time the cluster is put through the actuator test, the airbag indicator 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. The actuator test illumination of the airbag indicator is a function of the instrument cluster.

The ACM continually monitors the airbag system circuits and sensors to decide whether the system is in good oper-
ating condition. The ACM then sends the proper lamp-on or lamp-off messages to the instrument cluster. If the ACM
sends a lamp-on message after the bulb test, it indicates that the ACM has detected a system malfunction and/or
that the airbags and seat belt tensioners may not deploy when required, or may deploy when not required. The
ACM will store a Diagnostic Trouble Code (DTC) for any malfunction it detects. Each time the airbag indicator fails
to illuminate due to an open or short in the cluster airbag indicator circuit, the cluster sends a message notifying the
ACM of the condition, the instrument cluster and the ACM will each store a DTC, and the cluster will flash the
seatbelt indicator on and off as a backup to notify the vehicle operator.

For proper diagnosis of the airbag system, the ACM, the PCI data bus, or the electronic message inputs to the
instrument cluster that control the airbag indicator, a diagnostic scan tool is required. Refer to the appropriate diag-
nostic information.

BRAKE/PARK BRAKE INDICATOR

DESCRIPTION

A brake indicator is standard equipment on all instru-
ment clusters. This indicator is located near the lower
edge of the instrument cluster, between the tachome-
ter and the speedometer.

The brake indicator consists of a stencil-like cutout of the word “BRAKE” and the International Control and Display
Symbol icon for “Brake Failure” 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. A red Light Emitting Diode (LED)
behind the cutout in the opaque layer of the overlay causes the “BRAKE” text and icon to appear in red through the
translucent outer layer of the overlay when the indicator is illuminated from behind by the LED, which is soldered onto
the instrument cluster electronic circuit board. The brake indicator is serviced as a unit with the instrument cluster.

OPERATION

The brake indicator gives an indication to the vehicle operator when the parking brake is applied, when there are
certain brake hydraulic system malfunctions as indicated by a low brake hydraulic fluid level condition, or when the
brake fluid level switch is disconnected. The brake indicator can also give an indication when certain faults are
detected in the Antilock Brake System (ABS). This indicator is controlled by a transistor on the instrument cluster
circuit board based upon cluster programming, electronic messages received by the cluster from the Controller

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Antilock Brake (CAB) over the Programmable Communications Interface (PCI) data bus, and a hard wired input
from the park brake switch.

The brake 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 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 brake indicator for the following reasons:

•

Bulb Test - Each time the ignition switch is turned to the On position the brake indicator is illuminated by the
instrument cluster for about two seconds as a bulb test.

•

Brake Lamp-On Message - Each time the cluster receives a lamp-on message from the CAB, the brake indi-
cator will be illuminated. The CAB can also send brake lamp-on messages as feedback during ABS diagnostic
procedures. 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.

•

Park Brake Switch Input - Each time the cluster detects ground on the park brake switch sense circuit (park
brake switch closed = park brake applied or not fully released) while the ignition switch is in the On position,
the brake indicator flashes on and off. The indicator continues to flash until the park brake switch sense input
to the cluster is an open circuit (park brake switch open = park brake fully released), or until the ignition switch
is turned to the Off position, whichever occurs first.

•

Actuator Test - Each time the instrument cluster is put through the actuator test, the brake indicator 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.

The park brake switch on the park brake pedal mechanism provides a hard wired ground input to the instrument
cluster circuitry through the park brake switch sense circuit whenever the park brake is applied or not fully released.
The CAB continually monitors the ABS system circuits and sensors, including the brake fluid level switch on the
brake master cylinder reservoir, 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 cluster. If the CAB sends a lamp-on message after the
bulb test, it indicates that the CAB has detected a brake hydraulic 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.

For further diagnosis of the brake indicator or the instrument cluster circuitry that controls the LED, (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). The park brake switch input to the instru-
ment cluster can be diagnosed using conventional diagnostic tools and methods. Refer to the appropriate wiring
information. For proper diagnosis of the brake fluid level switch, the ABS, the CAB, the PCI data bus, or the elec-
tronic message inputs to the instrument cluster that control the brake indicator, a diagnostic scan tool is required.
Refer to the appropriate diagnostic information.

DIAGNOSIS AND TESTING

BRAKE INDICATOR

WARNING: To avoid personal injury or death, on vehicles equipped with airbags, disable the supplemental
restraint system before attempting any steering wheel, steering column, airbag, seat belt tensioner, impact
sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative
(ground) cable, then wait two minutes for the system capacitor to discharge before performing further diag-
nosis or service. This is the only sure way to disable the supplemental restraint system. Failure to take the
proper precautions could result in accidental airbag deployment.

The hard wired park brake switch input to the EMIC may be diagnosed and tested using conventional diagnostic
tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams,
proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out infor-
mation and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods may not prove conclusive in the diagnosis of the EMIC, the Controller
Antilock Brake (CAB), the Programmable Communications Interface (PCI) data bus, or the electronic message
inputs also used by the EMIC to provide brake indicator operation. The most reliable, efficient, and accurate means
to diagnose the EMIC, the CAB, the PCI data bus, and the electronic message inputs for the brake indicator oper-
ation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

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