The body control system consists of the following 3 modules:

Each of the 3 body control modules integrate a number of functional systems under the control of a single module. Each of the modules are connected to the Class 2 serial data line; many control signals are implemented by Class 2 messages.

The DIM is wired to the class 2 serial data line. The various DIM input and output circuits are described in the corresponding functional areas as indicated on the DIM electrical schematics.

The DIM functions include the following:

On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle the PMM is the DIM. The PMM receives 4 signals from the ignition switch.

To determine the correct power mode the PMM uses the following circuits:

Since the operation of the vehicle systems depends on the power mode, there is a fail-safe plan in place should the PMM fail to send a power mode message. The fail-safe plan covers those modules using exclusively serial data control of power mode as well as those modules with discrete ignition signal inputs.

Serial Data Messages

The modules that depend exclusively on serial data messages for power modes stay in the state dictated by the last valid PMM message until they can check for the engine run flag status on the serial data circuits. If the PMM fails, the modules monitor the serial data circuit for the engine run flag serial data. If the engine run flag serial data is True, indicating that the engine is running, the modules fail-safe to RUN. In this state the modules and their subsystems can support all operator requirements. If the engine run flag serial data is False, indicating that the engine is not running, the modules fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

Discrete Ignition Signals

Those modules that have discrete ignition signal inputs also remain in the state dictated by the last valid PMM message received on the serial data circuits. They then check the state of their discrete ignition input to determine the current valid state. If the discrete ignition input is active, battery positive voltage, the modules will fail-safe to the RUN power mode. If the discrete ignition input is not active, open or 0 voltage, the modules will fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

The DIM is able to control or perform all of the DIM functions in the wake-up state. The DIM enters the sleep state when active control or monitoring of system functions has stopped, and the DIM has become idle again. The DIM must detect certain wake-up inputs before entering the wake-up state. The DIM monitors for these inputs during the sleep state, where the DIM is able to detect switch transitions that cause the DIM to wake-up when activated or deactivated. Multiple switch inputs are needed in order to sense both the insertion of the ignition key and the power mode requested. This would allow the DIM to enter a sleep state when the key is IN or OUT of the ignition.

The DIM will enter a wake-up state if any of the following wake-up inputs are detected:

The DIM will enter a sleep state when all of the following conditions exist:

If all these conditions are met the DIM will enter a low power or sleep condition. This condition indicates that the DIM, which is the PMM of the vehicle, has sent an OFF-ASLEEP message to the other systems on the serial data line.

The IPM is wired to the class 2 serial data line. The various IPM input and output circuits are described in the corresponding functional areas as indicated on the IPM electrical schematics.

The IPM functions include the following:

The RIM is wired to the class 2 serial data line. The various RIM input and output circuits are described in the corresponding functional areas as indicated on the RIM electrical schematics.

The RIM functions include the following: