DeVille DTS V8-4.6L VIN 9 (2002)
Body Control Module: Description and Operation
Dash Integration Module (DIM)
General Description
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:
^
Class 2 communication requiring DIM interaction.
^
Control of exterior lamps.
^
Control of front foglights.
^
Control of the headlights.
^
Headlamps on with wiper input.
^
Hood ajar switch input w/export.
^
Horn relay control.
^
Interior lamps incandescent dimming.
^
Low side temperature for HVAC compressor.
^
Power moding control over Class 2 serial data circuit.
^
Reverse lockout solenoid control.
^
Steering wheel controls input.
^
Storage of the clock settings and, sending a message out on the class 2 serial data circuit in response to requests from other modules.
Serial Data Power Mode
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:
^
Accessory voltage
^
Ignition 1 positive voltage
^
Ignition 3 positive voltage
^
Off/Run/Crank voltage
Fail-Safe Operation
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.
DIM Wake-up/Sleep States
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:
^
Activity on the serial data line.
^
Detection of a battery disconnect and reconnect condition.
^
Door ajar switch.
^
Headlamps are on.
^
Hood ajar switch.
^
Ignition is turned ON.
^
Key-in-ignition switch.
^
Parklamps are on.
