GM Service Manual Online
For 1990-2009 cars only

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

Dash Integration Module (DIM)

The DIM functions include the following functions:

    • Power moding control (ignition switch states) over Class  2 serial data line
    • Control of headlights and exterior lamps
    • Interior lamps incandescent dimming
    • Steering wheel controls
    • Horn relay control for theft activation
    • Lamps On signal with wiper/washer
    • Low side temperature for HVAC compressor
    • Cooling fan control (power - train cooling)
    • Incandescent dimming of dash bulbs control
    • Real time clock time keeper
    • Battery voltage sense and load management
    • Reverse lockout solenoid control

Instrument Panel Module (IPM)

The IPM functions include the following functions:

    • Front HVAC air delivery and temperature controls
    • Ambient light sensor input and twilight delay input for headlights control
    • IP dimmer switch input
    • Traction control switch input
    • Interior lamps switch input
    • Key in ignition switch input from the ignition switch
    • Rear compartment lid release switch input
    • Ignition switch headlight control

Rear Integration Module (RIM)

The RIM functions include the following functions:

    • Heated seat controls
    • Rear defogger control
    • Park relay controls
    • Various controls for the interior lamps
    • Reverse control for the backup lamps
    • Rear compartment lid release controls
    • Retained Accessory Power (RAP) control
    • Ajar switch and tamper switch inputs from the rear compartment lid
    • Vehicle leveling