Class 2 Serial Data Line
Modules communicate along one common Purple wire referred to as class 2 serial data line. Serial data line is used to communicate information between systems. Each system on the serial data line is assigned its own identification number, which is used to identify itself to other modules or systems. Class 2 serial data line also allows communication with scan tool through Data Link Connector (DLC). See Fig 1 . Modules communicating along class 2 serial data line are as follow:
- Cellular Telephone Module
- Driver Door Module (DDM)
- Driver Door Switch Assembly (DDSA)
- Electronic Suspension Control Module
- Left Middle Door Module (w/V4U)
- Left Rear Door Module (LRDM)
- Memory Seat Module (MSM)
- Navigation Data Processor (w/UY4)
- Navigation Radio (w/UY4)
- Passenger Front Door Module (PFDM)
- Right Front Window Switch (w/B05)
- Radio Amplifier
- Rear Integration Module (RIM)
- Rear A/C-Heater Control
- Remote Function Actuator (RFA)
- Right Middle Door Module (w/V4U)
- Right Rear Door Module (RRDM)
- Steering Column Module
- Theft Deterrent Module
- Vehicle Interface Unit (On-Star(R))
Systems periodically send a State of Health (SOH) message to other systems. If those systems fail to send an SOH message back, a corresponding DTC will be set. Also, any system that cannot communicate properly will set a DTC.