Notes regarding Diagnostic trouble Code Memory To each fault (short circuit, open circuit etc) a certain numerical code has been assigned, i.e. Diagnostic Trouble Code (DTC). Additionally, current and intermittently appearing DTC's are differentiated from each other. When retrieving DTC's from the A/C pushbutton control module, short circuits and open circuits can not be differentiated from each other in every case. When reading out the DTC memory from any control module, all stored DTC's are shown, which means that some DTCs will be shown which do not apply to the current system being checked. Prerequisite for reading out DTC Memory Electrical wiring diagrams: Electrical Troubleshooting Manual, Model 163, Group 83 (available on the Workshop Information System [WIS] only).

DTC	Possible cause	Hint	Remedy
No communication using the HHT is possible.	Diagnostic line		23
No DTC stored	No DTC recognized.	Complaint valid and present: See A/C Electrical Test Program - Test	23
	Refrigerant pressure sensor (B12)		23 9.0
	Electromagnetic clutch (A9k1)		Wiring, A9k1