Audi Workshop Service and Repair Manuals > A4 Mk2 > Heating, ventilation, air conditioning system | Air conditioning | Self diagnosis, V.A.G Inspection Service | Checking convenience data bus system | Checking convenience data bus system | Convenience data bus system fault(s) only displayed by operating and display unit, Climatronic control unit J255

Convenience data bus system fault(s) only displayed by operating and display unit, Climatronic control unitJ255

Convenience data bus system fault(s) only displayed by operating and display unit, Climatronic control unit -J255-

–	Check encoding of operating and display unit, Climatronic control unit -J255- → Chapterand control unit in dash panel insert -J285- → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051 and → Electrical system; Rep. Gr.01.

–	Check signal wires to operating and display unit, Climatronic control unit -J255- for open circuit or wiring resistance. Wiring resistance: max. 1.5 ohms → Current flow diagrams, Electrical fault finding and Fitting locations

Note

Pay particular attention to the possibility of loose contacts in the wires and connectors.

If no fault can be found, the problem is in the operating and display unit, Climatronic control unit -J255-.