The BCM utilizes integrated circuitry and informa-
tion carried on the Programmable Communications
Interface (PCI) data bus network along with many
hard wired inputs to monitor many sensor and
switch inputs throughout the vehicle. In response to
those inputs, the internal circuitry and programming
of the BCM allow it to control and integrate many
electronic functions and features of the vehicle
through both hard wired outputs and the transmis-
sion of electronic message outputs to other electronic
modules in the vehicle over the PCI data bus.
OPERATION
The Body Control Module (BCM) supplies vehicle
occupants with visual and audible information and
controls various vehicle functions. To provide and
receive information, the BCM is interfaced to the
vehicle's serial bus communications network, referred
to as the Programmable Communications Interface
(PCI) bus.
This network consists of the;
²Powertrain Control Module (PCM)
²Transmission Control Module (TCM)
²Mechanical Instrument Cluster (MIC)
²Occupant Restraint Controller (ORC)
²Compass/Mini-Trip Computer (CMTC)
²Electronic Vehicle Information Center (EVIC)
²Controller Antilock Brake (CAB)
²HVAC Control Module
²Sliding Door Control Modules (driver and pas-
senger side doors)
²Power Liftgate Module (PLG)
²Audio system equipped with RAZ, RBU, RBK,
and RBB radios.
²Sentry Key Remote Entry Module (SKREEM).
²Side Impact Airbag Control Module (SIACM)²Memory Seat Module (MSM)
²Sentry Key Immobilizer Module (SKIM)
The BCM is operational when battery power is
supplied to the module.
The BCM provides the following features:
²Power Door Locks
²Automatic Door Locks
²Battery Protection - The BCM will automatically
turn off all exterior lamps after 3 minutes, and all
interior lamps after 15 minutes after the ignition is
turned off, if they are not turned off by the driver.
²Chime Control
²Compass/Mini-Trip support.
²Interior Lighting (Courtesy/Reading Lamps)
²BCM Diagnostic Reporting
²Electronic Liftgate Release (with Power Door
Locks)
²Exterior Lighting
²Headlamp Time Delay (with/without Automatic
Headlamps)
²Illuminated Entry
²Fade to Off Interior Lamps - This feature dims
the interior lighting (courtesy lamps) gradually if the
BCM does not receive any new inputs that would
cause the interior lamps to remain on.
²Pulse Width Modulated Instrument Panel Dim-
ming
²Door Lock Inhibit - This feature disables the
door lock functions if the key is in the ignition and
either front door is ajar. Pressing the Remote Keyless
Entry (RKE) lock/unlock button under these condi-
tions result in normal lock/unlock activation.
The BCM has the ability to LEARN additional fea-
tures in the vehicle, provided the appropriate switch
input and PCI data bus messages are received. Refer
to the LEARNED FEATURES table.
LEARNED FEATURES
FEATURE LEARNING KEY
REAR WIPER CONTROL ON HVAC CONTROL ON
INSTRUMENT PANELPCI BUS MESSAGE RECEIVED FROM HVAC
CONTROL
AUTOMATIC HEADLAMPS PCI MESSAGE FROM OVERHEAD OR HEADLAMP
SWITCH POSITION (AUTO)
REMOTE KEYLESS ENTRY SKREEM MESSAGE RECEIVED FROM MODULE
FRONT FOG LAMPS HEADLAMP SWITCH POSITION (PARK W/FRONT
FOG LAMPS)
POWER SLIDING DOOR PCI IFR RECEIVED FROM MODULE
THE BCM HAS FOUR SWITCH INPUTS FOR THE POWER SLIDING DOOR FEATURE; LOCATED IN THE
OVERHEAD CONSOLE ARE THE LEFT AND RIGHT SIDE SLIDING DOOR SWITCHES TO ACTIVATE EITHER
OR BOTH SLIDING DOORS UNDER THE PROPER CONDITIONS. ALSO ARE B-PILLAR SWITCHES LOCATED
ON THE LEFT AND RIGHT B-PILLAR POSTS.
POWER LIFTGATE PCI IFR RECEIVED FROM MODULE
RSELECTRONIC CONTROL MODULES8E-3
BODY CONTROL MODULE (Continued)
FEATURE LEARNING KEY
THE BCM HAS ONE LIFTGATE INPUT LOCATED IN THE OVERHEAD CONSOLE.
POWER LOCKOUT SWITCH INPUT
THE BCM HAS ONE LOCKOUT SWITCH INPUT THAT WHEN ENABLED WILL DISABLE THE B-PILLAR
SLIDING DOOR SWITCHES FROM ACTIVATING EITHER SLIDING DOOR WHEN DEPRESSED.
PCI AUDIO SYSTEM PCI MESSAGE RECEIVED FROM MODULE
REMOTE RADIO CONTROLS REMOTE RADIO SWITCHES PRESENT
VEHICLE THEFT SECURITY SKREEM MESSAGE RECEIVED, VALID KEY
RECEIVED, & DIAGNOSTIC PID RECEIVED.
MEMORY SEAT AND MIRRORS MEMORY SEAT SWITCH PRESENT AND OR PCI
MESSAGE RECEIVED FROM MEMORY MODULE
ABS W/TRACTION CONTROL PCI MESSAGE RECEIVED FROM CAB
SENTRY KEY IMMOBILIZER SYSTEM PCI MESSAGE RECEIVED FROM SKIM OR VTSS
PRESENT
ADJUSTABLE PEDAL MODULE PCI MESSAGE RECEIVED FROM ADJUSTABLE
PEDAL MODULE (APM)
When replacing a BCM there are three modules
available:
²Base
²Midline
²RG - Export
The Midline controller is used on vehicles that
have Power Door Locks. If a vehicle is equipped with
the Vehicle Theft Security System, the Midline con-
troller becomes a Premium when the theft feature is
enabled.
CAUTION: Do not swap Body Control Modules
between vehicles or body controller's off the shelf.
The BCM has internal diagnostic capability that
assists in diagnosing the system error. When an
OPEN or a SHORT circuit exists, the diagnostic tool
can be used to read the BCM faults. The faults are
very descriptive in identifying the appropriate fea-
ture that has faulted.
The only two faults that the BCM logs that con-
clude the replacement of a BCM are faults;
²# 01 - Internal BCM failure (replace BCM)
²# 1F - J1850 Internal Hardware Failure (replace
BCM)
Otherwise the appropriate diagnostic procedures
for each of the features should be taken when the
BCM logs a fault.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the lower instrument panel silencer.(3) Remove the knee blocker and reinforcement
(Refer to 23 - BODY/INSTRUMENT PANEL/KNEE
BLOCKER REINFORCEMENT - REMOVAL).
(4) Disconnect the five wire connectors from the
bottom of the Body Control Module (BCM).
(5) Move bulkhead wiring aside.
(6) Remove the screws holding the BCM to the
bulkhead.
(7) Remove the BCM from the mounting bracket.
INSTALLATION
(1) Install the BCM to the mounting bracket.
(2) Install the screws holding the BCM to the
bulkhead.
(3) Connect the five wire connectors to the bottom
of the Body Control Module (BCM).
(4) Install the knee blocker and reinforcement
(Refer to 23 - BODY/INSTRUMENT PANEL/KNEE
BLOCKER REINFORCEMENT - INSTALLATION).
(5) Install the lower instrument panel silencer.
(6) Connect the battery negative cable.
(7) Verify proper operation of BCM and its func-
tions.
CONTROLLER ANTILOCK
BRAKE
DESCRIPTION
The controller antilock brake (CAB) is a micropro-
cessor-based device which monitors the antilock
brake system (ABS) during normal braking and con-
trols it when the vehicle is in an ABS stop. The CAB
is mounted to the HCU as part of the integrated con-
trol unit (ICU) (Fig. 1). The CAB uses a 24-way elec-
8E - 4 ELECTRONIC CONTROL MODULESRS
BODY CONTROL MODULE (Continued)
The SKREES can be diagnosed and any stored DTC's
can be retrieved using a DRBllltscan tool as
described in the appropriate Body Diagnostic Proce-
dures information.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - SENTRY KEY
REMOTE ENTRY SYSTEM
WARNING: On vehicles equipped with airbags, refer
to electrical, restraints, warnings, before attempting
component diagnosis or service. Failure to take the
proper precautions could result in accidental airbag
deployment and possible personal injury or death.
NOTE: The following tests may not prove conclu-
sive in the diagnosis of this system. The most reli-
able, efficient, and accurate means to diagnose the
Sentry Key Remote Entry System (SKREES)
involves the use of a DRBIIITscan tool. Refer to the
proper Body Diagnostic Procedures information.
The Sentry Key Remote Entry System (SKREES)
and the Programmable Communication Interface
(PCI) bus network should be diagnosed using a scan
tool. The scan tool will allow confirmation that the
PCI bus is functional, that the Sentry Key Remote
Entry Module (SKREEM) is placing the proper mes-
sages on the PCI bus, and that the Powertrain Con-
trol Module (PCM) is receiving the PCI bus
messages. Refer to the proper Body Diagnostic Proce-
dures information, and Wiring Diagrams for complete
circuit descriptions and diagrams.
(1) Check the fuses in the Integrated Power Mod-
ule (IPM). If OK, go to Step 2. If not OK, repair the
shorted circuit or component as required and replace
the faulty fuse.
(2) Disconnect and isolate the battery negative
remote cable from the remote terminal. Unplug the
wire harness connector at the SKREEM. Check for
continuity between the ground circuit cavity of the
SKREEM wire harness connector and a good ground.
There should be continuity. If OK, go to Step 3. If not
OK, repair the open circuit to ground as required.
(3) Connect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
SKREEM wire harness connector. If OK, go to Step
4. If not OK, repair the open circuit to the fuse in the
IPM as required.
(4) Turn the ignition switch to the ON position.
Check for battery voltage at the fused ignition switch
output (run/start) circuit cavity of the SKREEM wire
harness connector. If OK, use a scan tool and the
proper Body Diagnostic Procedures information tocomplete the diagnosis of the SKREES. If not OK,
repair the open circuit to the fuse in the IPM as
required.
DIAGNOSIS AND TESTING - VEHICLE THEFT
SECURITY SYSTEM
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 har-
ness connectors, splices and grounds. Using a
DRBIIItscan tool. Refer to the proper Body Diagnos-
tic Procedures information for test procedures.
HOOD AJAR SWITCH -
EXPORT
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Using a small flat blade screwdriver, pry trig-
ger switch from the bracket on the left fender well.
(3) Disconnect the hood ajar switch from the wire
connector and remove from vehicle.
INSTALLATION
(1) Connect the hood ajar switch to the wire conec-
tor.
(2) Press the hood ajar switch into position on the
bracket located on the left inner fender well.
(3) Reconnect the battery negative cable.
(4) Close the hood and check for proper operation.
SENTRY KEY REMOTE ENTRY
MODULE
DESCRIPTION
The Sentry Key Remote Entry Module (SKREEM)
performs the functions of the Sentry Key Immobilizer
Module (SKIM), Remote Keyless Entry (RKE) Mod-
ule, and the Tire Pressure Monitoring (TPM) System
(previously part of the Electronic Vehicle Information
Center (EVIC).
The SKREEM is located in the same location as
the SKIM was and is mounted the same way. It looks
identical, but has added capabilities.
SENTRY KEY IMMOBILIZER
The Sentry Key Immobilizer System (SKIS)
authenticates an electronically coded Transponder
Key placed into the ignition and sends a valid/invalid
key message to the Powertrain Control Module
RSVEHICLE THEFT SECURITY8Q-3
VEHICLE THEFT SECURITY (Continued)
(PCM) based upon the results. The ªVALID/INVALID
KEYº message communication is performed using a
rolling code algorithm via the Programmable Com-
munication Interface (PCI) data bus. A ªVALID KEYº
message must be sent to the Powertrain Control
Module (PCM) within two seconds of ignition ON to
free the engine from immobilization.
The SKREEM contains a Radio Frequency (RF)
transceiver and a microprocessor. The SKREEM
retains in memory the ID numbers of any Sentry Key
that is programmed to it. The maximum number of
keys that may be programmed to each module is
eight (8). The SKREEM also communicates over the
Programmable Communication Interface (PCI) data
bus with the Powertrain Control Module (PCM), the
Body Control Module (BCM), the Mechanical Instru-
ment Cluster (MIC), and the DRB IIItscan tool. The
SKREEM transmits and receives RF signals through
a tuned antenna enclosed within a molded plastic
ring formation that is integral to the SKREEM hous-
ing. When the SKREEM is properly installed on the
steering column, the antenna ring fits snugly around
the circumference of the ignition lock cylinder hous-
ing. If this ring is not mounted properly, communica-
tion problems may arise in the form of transponder-
related faults.
For added system security, each SKREEM is pro-
grammed with a unique9Secret Key9code. This code
is stored in memory and is sent over the PCI bus to
the PCM and to each key that is programmed to
work with the vehicle. The9Secret Key9code is there-
fore a common element found in all components of
the Sentry Key Immobilizer System (SKIS). In the
event that a SKREEM replacement is required, the
9Secret Key9code can be restored from the PCM by
following the SKIM replacement procedure found in
the DRB IIItscan tool. Proper completion of this
task will allow the existing ignition keys to be repro-
grammed. Therefore, new keys will NOT be needed.
In the event that the original9Secret Key9code can
not be recovered, new ignition keys will be required.
The DRB IIItscan tool will alert the technician if
key replacement is necessary. Another security code,
called a PIN, is used to gain secured access to the
SKREEM for service. The SKREEM also stores in its
memory the Vehicle Identification Number (VIN),
which it learns through a bus message from the
assembly plant tester. The SKIS scrambles the infor-
mation that is communicated between its components
in order to reduce the possibility of unauthorized
SKREEM access and/or disabling.
REMOTE KEYLESS ENTRY (RKE)
The RKE transmitter uses radio frequency signals
to communicate with the SKREEM. The SKREEM is
on the PCI bus. When the operator presses a buttonon the transmitter, it sends a specific request to the
SKREEM. In turn the SKREEM sends the appropri-
ate request over the PCI Bus to the:
²Body Control Module (BCM) to control the door
lock and unlock functions, the liftgate lock and
unlock functions, the arming and disarming of the
Vehicle Theft Security System (VTSS) (if equipped),
and the activation of illuminated entry.
²Integrated Power Module (IPM) to activate the
park lamps, the headlamps, and the horn for horn
chirp. If requested, the BCM sends a request over
the PCI Bus to the:
TIRE PRESSURE MONITORING (TPM)
If equipped with the Tire Pressure Monitoring
(TPM) System, each of the vehicles four wheels will
have a valve stem with a pressure sensor and radio
transmitter built in. Signals from the tire pressure
sensor/transmitter are received and interpreted by
the SKREEM.
A sensor/transmitter in a mounted wheel will
broadcast its detected pressure once per minute
when the vehicle is moving faster than 15 mph (24
km/h). Each sensor/transmitter's broadcast is
uniquely coded so that the SKREEM can determine
the location.
OPERATION
SENTRY KEY IMMOBILIZER
The Sentry Key Remote Entry Module (SKREEM)
receives an encrypted Radio Frequency (RF) signal
from the transponder key. The SKREEM then
decrypts the signal and broadcasts the requested
remote commands to the appropriate modules in the
vehicle over the Programmable Communication
Interface (PCI) data bus. A valid transponder key ID
must be incorporated into the RF signal in order for
the SKREEM to pass the message on to the appro-
priate modules.
Automatic transponder key synchronization is done
by the SKREEM if a valid transponder key is
inserted into the ignition cylinder, and the ignition is
turned ON. This provides a maximum operation win-
dow for RKE functions.
Each Sentry Key Remote Entry System (SKREES)
consists of a SKREEM and a transponder key. Each
system has a secret key code unique to that system.
The secret key is electronically coded in the
SKREEM and in all programmed transponder keys.
It is used for immobilization and RKE functions for
data security. In addition, each transponder key will
have a unique identification. For North America, the
options are a 3-button or 6 button integrated keys.
For Export, the options are 2-button or 5 button key
fobs. (Export does not get the integrated key).
8Q - 4 VEHICLE THEFT SECURITYRS
SENTRY KEY REMOTE ENTRY MODULE (Continued)
(19) Disconnect the column harness wiring connec-
tors from the Brake Transmission Shift Interlock
(BTSI) and ignition switch (Fig. 11).
(20) Disconnect the column harness wiring connec-
tor for the multi-function switch (Fig. 12).(21) Disconnect the column harness wiring connec-
tors for the clockspring and SQUIB (Fig. 12).
(22) If equipped with Sentry Key Immobilizer, dis-
connect the wiring connector from the SKIM (Fig.
13).
(23) Remove screw fastening horn ground wire to
column (Fig. 14).
Fig. 11 Ignition Switch And BTSI Wiring
Connections
1 - WIRING CONNECTOR
2 - IGNITION SWITCH
3 - BTSI
4 - WIRING CONNECTOR
Fig. 12 Multi-function And Clockspring Wiring
Connections
1 - MULTI-FUNCTION SWITCH MOUNTING HOUSING
2 - MULTI-FUNCTION WIRING CONNECTOR
3 - CLOCKSPRING WIRING CONNECTOR
4 - CLOCKSPRING SQUIB WIRING CONNECTOR
Fig. 13 Sentry Key Immobilizer Module
1 - WIRING CONNECTOR
2 - IGNITION KEY CYLINDER HALO
3 - SKIM
4 - MOUNTING SCREW
Fig. 14 Horn Ground At Column
1 - STEERING COLUMN
2 - HORN GROUND WIRE
3 - SCREW
19 - 14 COLUMNRS
COLUMN (Continued)
(31) If the steering column is being replaced, slide
the multi-function switch mounting housing off the
column (Fig. 19).
(32) If the steering column is being replaced,
remove the mounting screw fastening the SKIM to
the ignition key cylinder housing (Fig. 13). Remove
the SKIM.
(33) If the steering column is being replaced,
remove the halo from the ignition key cylinder hous-
ing (Fig. 13).
(34) If the steering column is being replaced,
remove the ignition key lock cylinder (Refer to 19 -
STEERING/COLUMN/KEY/LOCK CYLINDER -
REMOVAL).
INSTALLATION
NOTE: Before proceeding, (Refer to 19 - STEERING/
COLUMN - WARNING)(Refer to 8 - ELECTRICAL/RE-
STRAINTS/DRIVER AIRBAG - REMOVAL).
NOTE: Make sure the front wheels of the vehicle are
still in the STRAIGHT AHEAD position before begin-
ning the column installation procedure.
(1) If removed, install the ignition key lock cylin-
der (Refer to 19 - STEERING/COLUMN/KEY/LOCK
CYLINDER - INSTALLATION).
(2) If removed, install the halo on the ignition key
cylinder housing (Fig. 13).(3) If removed, install SKIM (Fig. 13). Install the
mounting screw fastening the SKIM to the ignition
key cylinder housing. Tighten the screw to 4 N´m (30
in. lbs.) torque.
(4) If removed, slide the multi-function switch
mounting housing onto the column (Fig. 19).
(5) If multi-function switch mounting housing is
being installed, install the set-screw fastening the
housing to the column (Fig. 18). Tighten the set-
screw to 14 N´m (124 in. lbs.) torque.
(6) Install the steering column (Fig. 17). Slide the
column lower mounting slots over the lower mount-
ing studs (with nuts started) first, then lift column
into place over the upper mounting studs.
(7) Install the two upper mounting nuts (Fig. 17).
Tighten the two upper mounting nuts, then the two
lower mounting nuts to 12 N´m (105 in. lbs.) torque.
(8) Match the column shaft coupling to the inter-
mediate shaft and install the pinch bolt (Fig. 16).
Tighten the pinch bolt nut to 28 N´m (250 in. lbs.)
torque. Install the hair pin in the end of the pinch
bolt.
(9) Feed the shift cable through the bracket on the
column (Fig. 15), then install the clip fastening the
cable housing to the bracket.
(10) Connect the shift cable to the lever pin (Fig.
15).
(11) Install the screw fastening the horn ground
wire to the column (Fig. 14). Tighten the screw to 7
N´m (60 in. lbs.) torque.
(12) If equipped with Sentry Key Immobilizer, con-
nect the wiring connector to the SKIM (Fig. 13).
(13) Connect the column harness wiring connectors
for the clockspring and SQUIB (Fig. 12).
(14) Connect the column harness wiring connector
for the multi-function switch (Fig. 12).
(15) Connect the column harness wiring connectors
for the Brake Transmission Shift Interlock (BTSI)
and ignition switch (Fig. 11).
(16) Install the fixed shroud (Fig. 10). Install the
screws fastening the fixed shroud in place and
tighten the screws to 3 N´m (23 in. lbs.) torque.
(17) If equipped with Autostick, connect the wiring
connector (Fig. 9).
(18) If equipped with traction control, position the
upper shroud above the column and route the switch
wiring down around the column. Connect the wiring
connector from the column wiring harness to the
traction control switch wiring (attached to upper
shroud) (Fig. 9).
Fig. 19 Multi-Function Switch Mounting Housing
1 - MULTI-FUNCTION SWITCH MOUNTING HOUSING
2 - STEERING COLUMN
19 - 16 COLUMNRS
COLUMN (Continued)