The Body Control Module (BCM) is capable of accomplishing multiple body control functions. Components directly connected to the BCM are controlled by the BCM's outputs. The BCM can control its outputs based on input information it obtains from sensors and switches that are directly connected to the BCM, or by borrowing information from other vehicle systems connected to the Class 2 serial data link. The BCM evaluates this information and controls certain body systems by commanding an output on or off.

The BCM is also capable of commanding other vehicle systems to control functions that are not directly wired and/or controlled by the BCM. The BCM accomplishes this task by sending specific messages on the Class 2 serial data link. The vehicle system capable of performing such function will respond to the BCM message.

The BCM performs these functions:

Daytime running lamps (DRL).

The Passlock is a vehicle theft deterrent system. The Passlock theft deterrent system contains a Passlock sensor. The Passlock sensor is part of the ignition lock cylinder assembly. The Body Control Module (BCM) provides power and ground to the Passlock sensor. The Passlock sensor interfaces with the BCM through the Passlock detection circuit.

When turning the ignition switch to the start position with the proper key, the Passlock sensor generates an analog voltage signal. This signal is sent through the Passlock detecting circuit. This analog voltage signal is of a specific value to the vehicle, and varies from vehicle to vehicle. When attempting to start the engine, the BCM compares a preset stored analog voltage value with the signal coming from the sensor. Because both values match, the BCM sends a fuel enable password via the Class 2 serial data link to the Powertrain Control Module (PCM). As a result, the PCM enables the crank relay, and allows fuel delivery to the engine.

When attempting to start the engine by means other than using the proper key in the ignition switch, the Passlock sensor sends an analog voltage signal of a different value. The BCM compares the preset stored analog voltage value with the signal coming from the sensor. Because both values do not match, the BCM sends a fuel disable password via the Class 2 serial data link to the Powertrain Control Module (PCM). As a result, the PCM disables the crank relay, and does not allow fuel delivery to the engine.

The Accessory Power (RAP) feature allows the operation of the following functions for 10 minutes (or until a vehicle door opens) after the ignition switch has been turned from the ON or ACCESSORY position to the LOCK position:

Refer to Retained Accessory Power (RAP) Operation in Retained Accessory Power (RAP) for more information.

The BCM performs its functions in the wake-up state. The BCM enters the sleep state when active control or monitoring of system malfunctions has stopped, or when the BCM is idling. The BCM must detect certain wake-up inputs before entering the wake-up state. The BCM monitors its inputs during the sleep state, allowing the BCM to switch between the two states, awake or asleep.

The BCM enters the wake-up state when receiving activity on any of these inputs:

The sleep state is when the BCM has stopped active control and monitoring of system functions and has become idle again. For the BCM to enter the wake-up state, the BCM must detect a wake-up condition, mentioned previously. These conditions are called wake-up inputs that cause the BCM to change from a sleep to a wake-up state and begin active control and monitoring. The BCM has the ability to monitor for these wake-up inputs in the sleep state.

The BCM enters the sleep state when all of these conditions exist: