Absence of CAN bus 4 communication
• Trouble shoot CAN bus 4 cable harness and connectors. • Check connector for CAN bus 4 on MBS • Check wiring for CAN bus 4: - Measure the resistance (with the battery disconnected) between CAN-high and CAN-low. It should be close to 60 ohm (one 120 ohm termination resistor in each end of the CAN-bus). - Measure the resistance (with the battery disconnected) between CAN-high on MBSM and CAN-high on any other unit on CAN bus 4. It should be close to zero ohm. - Measure the resistance (with the battery disconnected) between CAN-low on MBS and CAN-low on any other unit on CAN-bus 4. It should be close to zero ohm.
What you'll see
Doors and the CCP may not work as intended.
System reaction
Functions dependent on information on CAN bus 4 are degraded/missing in MBS (Master); Mainly door and climate system functionalities.
Diagnostic depth
The fault is validated as present if the ECU does not detect communication on CAN bus 4 within the timeout period
• Defect wiring for CAN bus 4. • Defect ECU unit(s) on the CAN bus 4.