Comfort Data Bus System Faults Displayed By Climatronic Control Module A/C Control Head

Comfort Data Bus System, Checking

• If the connector is disconnected from a control module connected to the comfort data bus system and the ignition is switched on, a fault entry can occur in the other control modules connected to the comfort data bus system. The same is true if the voltage supply is interrupted by activation of a fuse for example.

• The instrument cluster control module (J285) forms the interface between the two data bus systems. It is also the determining control module in the comfort data bus system. Via adaptation the control modules connected to the comfort data bus system in this vehicle are entered (equipment-dependent). Refer to => Vehicle Diagnosis, Testing and Information System VAS 5051 in the "guided fault finding" function.

• The wiring diagrams can be used to determine how many control modules are connected to the comfort data bus system.

Comfort Data Bus System Faults Displayed by Climatronic Control Module A/C Control Head

- Check the coding of the Climatronic control module (J255). Refer to => [ A/C Control Head Climatronic Control Module, Coding ] A/C Control Head Climatronic Control Module, Coding A/C control head and the instrument cluster control module ( J285). Refer to => Vehicle Diagnosis, Testing and Information System VAS 5051 in the "guided fault finding" function.

- Check the data lines to the Climatronic control module (J255) A/C control head for open circuit or line resistance. Line resistance: max. 1.5 ohms.

• Pay particular attention to possible loose contacts in the wire connections and plug connections.

If no fault can be identified, the fault is in the Climatronic control module (J255) A/C control head.