Body Control Module: Description and Operation

DASH INTEGRATION MODULE (DIM)
The dash integration module (DIM) controls the exterior lighting and the horn activation. When the RIM detects an unauthorized entry, the RIM sends a message via the serial data circuit to the DIM to activate the horns and exterior lamps. The DIM then grounds the appropriate relays to control the exterior lighting and horns.

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:
- A/C refrigerant low temperature sensor signal.
- Air conditioning orifice solenoid control.
- Backlight lamps control.
- Control of headlights and exterior lamps.
- Control power control.
- DRL relay control.
- Flash to pass signal.
- Headlamps on w/wipers signal.
- Headlamps switch signal.
- Horn relay control.
- Interior lamps incandescent dimming.
- Power moding control over Class 2 serial data line.
- Reverse lockout solenoid control.
- Storage of the clock settings and, sending a message out on the class 2 serial data circuit in response to requests from other modules.
- Steering wheel controls.

INSTRUMENT PANEL MODULE (IPM)
The various IPM input and output circuits are described in the corresponding areas as indicated on the IPM electrical schematics. The IPM functions include the following:
- Ambient light sensor input and twilight delay input for headlights control.
- Foglamp switch input.
- Front HVAC air delivery and temperature controls.
- Ignition switch headlight control.
- Interior lamps switch input.
- I/P dimmer switch input.
- Key cylinder lamp control.
- Key-in-ignition switch input from the ignition switch.
- Rear compartment lid release switch input.
- Traction control switch input.

REAR INTEGRATION MODULE (RIM)
The CTD system is an internal function of the rear integration module (RIM) which utilizes class 2 serial data circuit and various switch input information to perform CTD functions. When RIM detects an unauthorized entry, the RIM sends a message via the serial data circuit to the DIM to activate the horns and exterior lamps. The RIM has 5 basic modes (disarmed, standby, delayed, armed, and alarm) for operating the CTD system. The 5 modes transition from one step to the next in the following order:
1. When in the disarmed mode, ignition is OFF and any door is open the RIM commands the instrument cluster to flash the SECURITY indicator via the class 2 serial data circuit. The RIM has the CTD system in a disarmed mode until the following conditions are detected:
- Ignition key turned to the OFF position
- Any door open
- Doors locked by either the power door lock switch or the LOCK button on the transmitter
2. The RIM enters the standby mode when the above conditions are detected. In standby mode the RIM commands the instrument cluster to illuminate the SECURITY indicator via the class 2 serial data circuit. If all the doors are closed and the LOCK button on the transmitter is used, the RIM enters the delayed mode.
3. When the last door is closed, the RIM enters the delayed mode for 30 seconds. In delayed mode the RIM commands the instrument cluster to illuminate the SECURITY indicator via the class 2 serial data circuit.
4. After 30 seconds, the RIM enters the armed mode. In armed mode the RIM commands the instrument cluster to turn off the SECURITY indicator via the class 2 serial data circuit. Any forced entry activates the alarm mode.

IMPORTANT: The CTD system can be armed with the windows or sunroof open.

5. When the RIM detects a forced entry, the RIM enters the alarm mode. The RIM commands the DIM to activate the horn and exterior lamps for 30 seconds, via a class 2 message. This is followed by a 3 minute time-out of the horns, during the time-out period the horns are no longer active. If no new intrusions are detected during the time-out, the horn is not active. The system must be disarmed or the intrusion condition removed after the time-out for the system to exit alarm mode.

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:
- Automatic level control.
- CIGAR relay control.
- Fuel door release relay control.
- Heated seat controls.
- Heating, ventilation, and air conditioning (HVAC) blower control.
- Inadvertent power relay control.
- Park brake relay controls.
- Rear defogger relay control.
- Rear foglamp relay control.
- Retained accessory power (RAP) control.
- Reverse lamp relay control.
- Trunk ajar switch signal.
- Trunk release relay control.
- Various controls for the interior lamps.