Class 2 Serial Data Link

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

Scan tool will power up with ignition switch in OFF position. Some modules will not communicate unless ignition switch is in RUN position and Power Mode Master (PMM) module (DIM) sends appropriate power mode message. Data link is configured as a ring with discrete lines entering and leaving each module. This allows communication with modules on ring if one of two discrete circuits is open. Modules on data link include:

Driver Door Module (DDM)
Dash Integration Module (DIM)
Driver Information Center (DIC)
Electronic Brake Control Module (EBCM)
Instrument Panel Cluster (IPC)
Instrument Panel Module (IPM)
Memory Seat Module (MSM)
Powertrain Control Module (PCM)
Radio
Rear Integration Module (RIM)
Remote Control Door Lock Receiver (RCDLR)
Sensing & Diagnostic Module (SDM)
CD Changer
Theft Deterrent Control (TDC) Module
Vehicle Communication Interface Unit (VCIM)
Vehicle Interface Unit (VIU)

DDM, MSM, VCIU and VIU have only one connection to data link wiring.

Power door serial data circuit does not communicate with scan tool via DLC. Power door serial data information is interpreted by Driver Door Module (DDM) and transmitted on Class 2 data link by DDM. Door system serial data circuit is used for serial data communication between each door module and driver door switch assembly (DDSA).