GM Service Manual Online
For 1990-2009 cars only

The body control system consists of the following 3 modules:

    • The dash integration module (DIM)
    • The instrument panel integration module (IPM)
    • The rear integration module (RIM)

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.

Dash Integration Module (DIM)

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:

    • Control of headlights and exterior lamps
    • Horn relay control
    • Interior lamps incandescent dimming
    • Lamps On signal with wiper/washer
    • Power moding control over Class  2 serial data line. Refer to Power Mode Description and Operation
    • Steering wheel controls
    • Storage of the clock settings and, sending a message out on the class 2 serial data circuit in response to requests from other modules

Instrument Panel Integration Module (IPM)

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 ambient light sensor input and twilight delay input for headlamp control.
    • The front HVAC air delivery and temperature control.
    • The IP dimmer switch input.
    • The ignition switch headlamp control.
    • The interior lamps switch input.
    • The key-in-ignition switch input from the ignition switch.
    • The rear compartment lid release switch input.
    • The traction control switch input.

Rear Integration Module (RIM)

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:

    • The ajar switch and tamper switch inputs from the rear compartment lid
    • The automatic level control
    • The cigar lighter relay control
    • The fuel door lock and release control
    • The heated seat controls
    • The park brake relay control
    • The rear compartment lid release controls
    • The rear defogger relay control
    • The retained accessory power (RAP) relay control
    • The reverse lamp relay control
    • The various controls for the interior lamps

Power Mode Master

This vehicles DIM functions as the Power Mode Master (PMM). Refer to Power Mode Description and Operation for a complete description of power mode functions.