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Home >> Jeep >> 2009 >> Commander Overland, RWD >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Electronic Shift Module (ESM) - Electrical Diagnostics >> DTC Troubleshooting >> U0121-Lost Communication With Anti-Lock Brake Module >> Theory Of Operation
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Theory Of Operation

Some controllers communicate with other controllers over the CAN C bus. The Shift Lever Assembly (SLA) contains a Electronic Shift Module (ESM) that continuously monitors the bus activity and receives the messages it needs. The CAN C bus is also used to communicate transmission MIL status to the Engine Controller.