Body Control Module: Description and Operation

The BPM electronically controls many vehicle functions. It responds when a switch is actuated by providing output signals to the appropriate devices, either directly or indirectly via relays. In addition the BPM establishes an ISO network link with the Security and Locking Control Module (SLCM) and utilizes the SCP network to exchange data between the body system modules.

The following tables are published for guidance purposes and only provide a rough indication of the correlation between circuit inputs and outputs; due to the complexity and necessary functional interaction required for the vehicle there are many circuits where inputs and outputs overlap.

Malfunction of modules must always be analyzed using the PDU as recommended in System Diagnosis.

Inputs/outputs

Exterior lights circuit
BPM inputs from: BPM outputs to:
Front fog switch Front fog relay
Rear fog switch Low beam relay
Low beam switch High beam relay
High beam switch Side marker and license plate relay
Side lights switch Side and tail lights
Headlamp flash switch Direction indicators
Direction indicator switch Hazard status bulb
Hazard switch Indicators via SCP
Front fog
Low beam
High beam
Side light
Direction
Hazard warning
Status LEDS
Front fog
Rear fog

NOTE: The reverse lights and rear fog lights are NOT controlled by the BPM but by the Security and Locking Control Module.

Interior lights circuit
BPM inputs from: BPM outputs to:
Header console courtesy light switch Instrument and switch Illumination.
Fade 1 (Header console courtesy lamps)
SCP Fade 2 (E-post courtesy lamps)
Map lights
Sun visor lamps
Glovebox lamp
Trunk lamps

Washer/wiper circuit
Wiper park switch Power wash relay
Low screen wash switch Wiper motor run
Wiper slow speed switch Screen wash pump
Wiper fast speed switch Wiper fast/slow speed
Wiper intermittent switch
Wash/wipe switch

Ignition circuit
Ignition position Transit relay
Auxiliary position Mirror fold out
Mirror fold flat

Central door locking circuit
Central locking button Central door locking relay
Valet switch SCP (door modules, security and locking control module)
SCP (door modules) Sun roof ECU

Security system circuit
Hood security switch Horn relay
Horn switches Active security sounder
Central locking button Passive security sounder
SCP (door modules, security and
locking control module) Security status LED
ISO link (key transponder module) Central door locking relay
SCP (door modules, security and locking control module)
ISO link (key transponder module)

Steering column adjustment circuit
Column adjustment switches Column tilt motor
Column reach motor

Gear shift interlock circuit
Neutral switch Keylock solenoid
J-gate not in park Gearshift interlock solenoid

Seat heaters circuit
Seat heater switches Seat heater relay
Status LED

Seat buckle circuit
Seat buckle Audible warning
SCP