Grand Cherokee 2WD V8-4.7L VIN J (2004)
Body Control Module: Description and Operation
Body Control Module Description
The body control module (BCM) supplies vehicle occupants with visual and audible information and controls various vehicle functions. To provide and
receive information, the module is interfaced to the vehicle's serial bus communication network (Programmable Communication Interface or PCI bus).
This network consists of the powertrain control module (PCM) or engine control module (ECM) (diesel), the memory/heated seat module (MHSM,
MSM or HSM), the sentry key immobilizer module (SKIM), the transmission control module (TCM), the electro/mechanical instrument cluster (MIC),
the driver door module (DDM), the passenger door module (PDM), the airbag control module (ACM), the controller antilock brake (CAB), the optional
electronic vehicle information center (EVIC), the optional PCI radio, the optional CD changer, the optional automatic zone control module (AZC), the
shifter assembly (diesel), the optional power amplifier, the optional adjustable pedal module, the optional rain sensor, and the optional intrusion
transceiver module (export). The BCM is operational when battery power is supplied to the module and in addition, ignition switch power is needed for
ignition switched functions.
The BCM provides the following features:
-
Full control of all exterior and interior lamps, including these features:
-
A Battery Saver automatically turns off all exterior and interior lamps within 8 minutes after the ignition is turned off, if they are not turned off
by the driver. This includes the front and rear reading/courtesy lamps and the cargo area dome lamp, even if they are turned on manually.
-
Theater-style interior lighting dims gradually when the doors are closed.
-
Interior courtesy lamp operation may be "defeated" using the dimmer control ring on the left multifunction switch.
-
Instrument panel light intensity may be maximized for daytime visibility with the head lamps or parking lights by using the dimmer control
ring on the left multifunction switch.
-
An Accessory/Sunroof Delay allows continued operation of the sunroof and the power windows after ignition-OFF. These accessories can be
operated up to 45 seconds after ignition-OFF or until door is opened.
-
Beep tones for warnings and programming actions associated with the Sentry Key Immobilizer system and the EVIC. The BCM also provides the
following features:
-
Intermittent wipe and low speed wiper control
-
Wiper system status
-
Ignition on/off timer
-
VF displays synchronization
-
Rear door and liftgate ajar status
-
Acquisition & transmission of external temperature
-
A/C select switch status
-
Chime
-
Courtesy lamps with fade to off feature
-
Reading lights/glove box lamp load shedding control
-
Exterior lighting control including automatic headlamps, fog lamp control, rear fog lamp control and parking lamps
-
Exterior lamp status
-
Headlamp time delay upon ignition off and headlamps switch off
-
Parade mode
-
Illuminated entry
-
Instrument panel dimming
-
Vehicle theft security system with panic & horn and hazard lamp activation
-
Key-in ignition switch interface
-
Brake fluid level switch/park brake switch interface
-
Seatbelt reminder
-
Speed sensitive intermittent wipe control
-
Remote radio switch interface to radio
-
Vehicle ignition status
-
BCM self diagnostics
-
Liftgate courtesy lamp disable
-
Rear window defogger control
-
Accessory delay control (windows and sunroof)
-
Fuel economy and distance to empty (DTE) calculations
-
Heated seat switch status
-
Exterior lamp load shed
-
Support of EVIC programmable features
-
Radio EQ curve setting
The BCM receives information over the PCI bus from the PCM in order to support certain features. The required information is as follows:
-
Engine RPM
-
Engine and battery temperature
-
Injector on time and distance pulses
-
Vehicle speed
-
Engine model
-
Fuel tank level
