Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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). Modules communicating along class 2 serial data line are as follow:
- A/C-Heater Control Panel
- A/C-Heater Programmer
- Cellular Telephone Module
- Continuously Variable Road Sensing Suspension (CVRSS) Module
- Electronic Brake Control Module (EBCM)
- Instrument Panel Cluster (IPC)
- Memory Mirror Module (MMM)
- Memory Seat Module (MSM)
- Platform Zone Module (PZM)
- Powertrain Control Module (PCM)
- Radio
- Radio Interface Module (RIM)
- Remote Function Actuator (RFA)
- Sensing And Diagnostic Module (SDM)
- Vehicle Interface Unit (VIU)
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.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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