Description & Operation

WARNING: Vehicle is equipped with air bag supplemental restraint system. Before attempting ANY repairs involving steering column, instrument panel or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEM article.

NOTE: Body Control Module (BCM) may be referred to as Platform Zone Module (PZM).

The Body Control Module (BCM) performs the following functions: HVAC afterblow control, battery guard, door lock and unlock, fuel level for DIC, retained accessory power, theft deterrent, exterior and interior lighting control, trunk release, time of day for radio display, rear defog, fuel door release, and vehicle personalization.

Signals that activate the BCM are known as "wake-up" signals. BCM is asleep when it is not controlling or monitoring the following wake-up functions: Key in door lock switch, door ajar switches, power door lock switches, trunk ajar switch, trunk tamper switch, ignition on, ignition accessory (ACC), and any class 2 communication requiring PZM interaction.

BCM uses class 2 serial data line to communicate with other system control modules. Class 2 serial data is transmitted on a single wire at an average of 10.4 Kbps (10,400 bits per second). Class 2 uses a variable pulse width modulation to carry data, and speed is determined by message being transmitted. The bus is active at 7 volts nominal and inactive at ground potential. Class 2 serial data line is tolerant to different levels of ground potential.