Jeep Liberty KJ. Manual - part 1482

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Interior Lighting Control - The BCM monitors inputs from the interior lighting switch, the door ajar switches,
the flip-up glass ajar switch, the tailgate ajar switch, the cargo lamp switch, the reading lamp switches, and the
RKE system to provide courtesy lamp control. This includes support for timed illuminated entry with theater-
style fade-to-off and courtesy illumination defeat features.

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Intermittent Wipe and Front Wiper System Control - The BCM monitors inputs from the front wiper and
washer switch and the front wiper motor park switch to provide front wiper system control through the wiper
on/off and high/low relays. This includes support for adjustable intermittent wipe, mist wipe (also known as
pulse wipe), and wipe-after-wash features.

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Key-In-Ignition Switch Status - The BCM monitors and transmits the status of the key-in-ignition switch.

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Panic Mode - The BCM provides support for the RKE system panic mode feature.

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Parade Mode - The BCM provides a parade mode (also known as funeral mode) that allows the interior Vac-
uum Fluorescent Displays (VFD) to be illuminated at full intensity while driving in daylight with the exterior
lamps On.

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Power Locks - The BCM monitors inputs from the power lock switches and the RKE system to provide control
of the power lock motors through outputs to the lock, unlock, and driver unlock relays. This includes support
for rolling door locks (also known as automatic door locks) and a door lock inhibit mode.

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Programmable Features - The BCM provides support for several standard and optional programmable fea-
tures, including: rolling door locks, headlamp time delay interval, RKE driver-door-only or unlock-all-doors, RKE
optical chirp, and RKE audible chirp.

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Remote Keyless Entry - The BCM provides support for the RKE system features, including support for the
RKE Lock, Unlock (with optional driver-door-only unlock, and unlock-all-doors), rear flip-up glass control, Panic,
audible chirp, optical chirp, and illuminated entry modes.

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Rolling Door Locks - The BCM provides support for the power lock system rolling door locks feature (also
known as automatic door locks).

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Tailgate and Flip-Up Glass Ajar Status - The BCM monitors and transmits the status of the tailgate and rear
flip-up glass ajar switches.

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Remote Radio Switch Interface - The BCM monitors and transmits the status of the optional remote radio
switches.

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Self-Diagnostics - The BCM provides support for diagnostics through communication with a diagnostic scan
tool over the PCI data bus network. Each analog and digital input can be verified, and each output can be
actuated through the use of this diagnostic protocol. The BCM also stores Diagnostic Trouble Codes (DTCs) to
assist in the troubleshooting of this unit.

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Vacuum Fluorescent Display Synchronization - The BCM transmits panel lamp intensity data which allows
modules with Vacuum Fluorescent Displays (VFD) to coordinate their illumination intensity.

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Vehicle Theft Security System - The BCM monitors inputs from the door ajar switches, the tailgate ajar
switch, the flip-up glass ajar switch, the hood ajar switch (in required markets only), and the RKE system to
control the features of the optional Vehicle Theft Security System (VTSS).

Hard wired circuitry connects the BCM to the electrical system of the vehicle. These hard wired circuits are integral
to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These
circuits may be connected to each other, to the vehicle electrical system and to the BCM through the use of a
combination of soldered splices, splice block connectors, and many different types of wire harness terminal con-
nectors and insulators. Refer to the appropriate wiring information. The wiring information includes wiring diagrams,
proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-
out and location views for the various wire harness connectors, splices and grounds.

Many of the electronic features in the vehicle controlled or supported by the BCM are programmable using a cus-
tomer programming procedure or a diagnostic scan tool. In addition, the BCM software is Flash compatible, which
means it can be reprogrammed using Flash reprogramming procedures. However, if any of the BCM hardware is
damaged or faulty, the entire BCM unit must be replaced.

8E - 140

ELECTRONIC CONTROL MODULES

OPERATION

The microprocessor-based Body Control Module (BCM) monitors many hard wired switch and sensor inputs as well
as those resources it shares with other electronic modules in the vehicle through its communication over the Pro-
grammable Communications Interface (PCI) data bus or the hybrid bus network. The internal programming and all
of these inputs allow the BCM microprocessor to determine the tasks it needs to perform and their priorities, as well
as both the standard and optional features that it should provide. The BCM programming then performs those tasks
and provides those features through both PCI data bus or hybrid bus communication with other electronic modules
and through hard wired outputs through a number of driver circuits, relays, and actuators. These outputs allow the
BCM the ability to control numerous accessory systems in the vehicle.

The BCM operates on battery and ignition voltage inputs received through several fuses in the Junction Block (JB)
on a non-switched fused B(+) circuit, through another fuse in the JB on a fused ignition switch output (run-start)
circuit, and through a third fuse in the JB on a fused ignition switch output (run-acc) circuit. This arrangement allows
the BCM to provide some features regardless of the ignition switch position, while other features will operate only
with the ignition switch in the On, Start, and/or Accessory positions. All of the battery voltage circuits are connected
to the BCM through the JB/BCM connector.

The BCM receives ground through five separate circuits. Three of these circuits are connected to the BCM through
a connector of the instrument panel wire harness on three separate ground circuits, while the other two circuits are
connected to the BCM through the JB/BCM connector. Each of these circuits receives a path to ground through the
instrument panel wire harness with an eyelet terminal connector that is secured by a nut to a ground stud on the
driver side instrument panel end bracket near the JB.

The BCM monitors its own internal circuitry as well as many of its input and output circuits, and will store a Diag-
nostic Trouble Code (DTC) in electronic memory for any failure it detects. These DTCs can be retrieved and diag-
nosed using a diagnostic scan tool. Refer to the appropriate diagnostic information.

INPUT AND OUTPUT CIRCUITS

HARD WIRED INPUTS

The hard wired inputs to the BCM include the following:

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A/C on/off control

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BCM flash enable

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Door lock switch mux

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Driver door ajar switch sense

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Flip-up glass ajar switch sense

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Flip-up glass release switch sense

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Front fog lamp switch sense

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Front wiper park switch sense

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Front wiper switch mux

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Fused B(+)

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Fused ignition switch output (run-acc)

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Fused ignition switch output (run-start)

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Headlamp switch mux

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High beam switch sense

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Hood ajar switch sense - with VTSS - in markets where required only

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Key-in ignition switch sense

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Left rear door ajar switch sense

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Lightbar switch sense - Renegade with light bar only

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Panel lamps dimmer switch mux

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Passenger front door ajar switch sense

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Radio control mux - with remote radio switches only

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Rear courtesy lamp control

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Rear window defogger control

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Rear wiper intermittent driver

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Rear wiper on driver

ELECTRONIC CONTROL MODULES

8E - 141

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RHD input - connected to ground on right-hand drive models only

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Right rear door ajar switch sense

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Tailgate ajar switch sense

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Washer pump driver

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Vehicle speed signal

Refer to the appropriate wiring information for additional details.

HARD WIRED OUTPUTS

The hard wired outputs of the BCM include the following:

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Accessory delay relay control - power sunroof only

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Courtesy lamp driver

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Courtesy lamp load shed

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Door lock relay control

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Door unlock relay control

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Driver door unlock relay control

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Flip-up glass release motor driver

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Front fog lamp relay control

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Front wiper high/low relay control

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Front wiper on/off relay control

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Fused B(+) - lock, unlock and driver unlock relay feed

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Hazard lamp control

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High beam relay control

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Horn relay control

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Instrument cluster wake up signal

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Low beam relay control

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Park lamp relay control

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Rear fog lamp relay control - with rear fog lamps in markets where required only

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Rear window defogger relay control

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Tailgate lock driver

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Tailgate unlock driver

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Vehicle speed output

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Vehicle speed sensor supply - except with Antilock Brake System (ABS)

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VTSS indicator driver - with VTSS only

Refer to the appropriate wiring information for additional details.

GROUNDS

The BCM receives ground through five separate circuits, and also supplies a clean ground path to several switches
through the following hard wired circuits:

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Door lock switch ground

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Multi-function switch ground

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Radio control mux return

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Tailgate switch ground

Refer to the appropriate wiring information for additional details.

COMMUNICATION

The BCM has the following communication circuits:

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PCI bus

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CAN-C High bus - with ESP only

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CAN-C Low bus - with ESP only

Refer to the appropriate wiring information for additional details.

8E - 142

ELECTRONIC CONTROL MODULES

DIAGNOSIS AND TESTING

BODY CONTROL MODULE

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, occupant classification sys-
tem, 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 diagnosis 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 inputs to and outputs from the Body Control Module (BCM), as well as other hard wired circuits for
this module may be diagnosed and tested using conventional diagnostic tools and procedures. Refer to the appro-
priate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair proce-
dures, details of wire harness routing and retention, connector pin-out information 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 BCM, the Programma-
ble Communications Interface (PCI) data bus, or the electronic messages received and transmitted by the BCM over
the PCI data bus. The most reliable, efficient, and accurate means to diagnose the BCM, the PCI data bus and the
electronic message inputs to and outputs from this module requires the use of a diagnostic scan tool. Refer to the
appropriate diagnostic information.

REMOVAL

NOTE: Before replacing a Body Control Module (BCM), use a diagnostic scan tool to retrieve the current
settings for the many BCM programmable features including electronic pinion factor (tire size), cabin equal-
ization curve (audio system architecture), country code and Remote Keyless Entry (RKE) system prefer-
ences. These settings MUST be programmed into the replacement BCM using the diagnostic scan tool
before returning the vehicle to service. A new BCM is shipped in default mode that may prevent proper
speedometer indications and the availability of numerous electronic features until it has been properly pro-
grammed. Refer to the appropriate diagnostic information.

1. Disconnect and isolate the battery negative cable.

2. Remove the Junction Block Module (JBM) (3) from

the instrument panel end bracket on the driver side
of the vehicle. (Refer to 8 - ELECTRICAL/POWER
DISTRIBUTION/JUNCTION BLOCK - REMOVAL).

3. Remove the four screws (1) that secure the Body

Control Module (BCM) (2) to the Junction Block
(JB).

4. Remove the BCM from the JB.

ELECTRONIC CONTROL MODULES

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