Output Diagnostic Test Mode (DTM) (function 03)

Note the following as regards Output Diagnostic Test Mode (DTM) diagnosis 

• The A/C Compressor Regulator Valve N280 is only activated by the operating and display module, Climatronic Control Module J255 with the engine stopped.
• The request for activation of the Coolant fan (speed "1" and speed "2") is always transmitted by the operating and display module, Climatronic Control Module J255 to the relevant engine control module. However, the engine control module only switches on the fan(s) if the engine is running "Guided Fault-Finding" Vehicle Diagnosis, Testing Info. System VAS5051B or Vehicle Diagnosis Service Syst. VAS5052.
• Output Diagnostic Test Mode (DTM) diagnosis can only be implemented up to an engine speed of 3000 RPM and at vehicle speeds below 5 km/h.
• For install locations of components activated, refer to → A/C system control and regulation components .

• If necessary, Output Diagnostic Test Mode (DTM) diagnosis can be repeated several times.
• Control element malfunctions are stored in the DTC memory.
• Control action and the display of the operating and display module, Climatronic Control Module J255 are deactivated during Output Diagnostic Test Mode (DTM) diagnosis (depending on version, 22 °C appears for example in both displays). The "segment test" function is the only function during which the display segments of the operating and display module, Climatronic Control Module J255 are activated.
• The air conditioner control motors are moved into a predetermined position by the operating and display module, Climatronic Control Module J255 after selecting the "Output Diagnostic Test Mode (DTM) diagnosis" function. During Output Diagnostic Test Mode (DTM) diagnosis, it is therefore not necessary to wait for the control motors to reach a specified position.