Output Diagnostic Test Mode (DTM) (Function 03)

Output Diagnostic Test Mode (DTM) (Function 03)

NOTE:
- This Repair Manual only gives an outline of the "output Diagnostic Test Mode (DTM)" function. If the "output Diagnostic Test Mode (DTM)" function is performed as part of Guided Fault Finding, appropriate notes are then given on operation of the various components during output Diagnostic Test Mode (DTM).
- Note the following as regards output Diagnostic Test Mode (DTM):
- Request for actuation of radiator fans (0 to 100%) is transmitted by Climatronic Control Module -J255- to the appropriate Engine Control Module (ECM). Fan is however only switched on by Engine Control Module (ECM) when engine is running.
- Output Diagnostic Test Mode (DTM) can only be implemented at vehicle speeds below 5 km/h.
- Output Diagnostic Test Mode (DTM) can be repeated several times if necessary.
- Control element malfunctions are stored in DTC memory.
- During output Diagnostic Test Mode (DTM), air conditioner regulation and display of Climatronic Control Module -J255- (Rear A/C Control Head (Climatronic) -E265-) are deactivated. Segments of Climatronic Control Module -J255- (Rear A/C Control Head (Climatronic) -E265-) display are only actuated during "segment test" function.
- Air conditioner control motors are moved into a pre-determined position by Climatronic Control Module -J255- (Rear A/C Control Head (Climatronic) -E265-) after selecting "Output Diagnostic Test Mode (DTM)" function. During output Diagnostic Test Mode (DTM), it is therefore not necessary to wait for control motors to reach a specified position.

Starting output Diagnostic Test Mode (DTM)
- With ignition off, connect up vehicle diagnostic, testing and information system VAS 5051 with diagnostic cable VAS 5051/5A to 16-pin Data Link Connector (DLC) in vehicle.
- Switch on ignition/start engine.

NOTE:
- Switch on ignition (no engine operation) for checking actuation of A/C Compressor Regulator Valve -N280-.
- Start engine for actuation of radiator fans.

- Set "Auto" mode on Climatronic Control Module -J255- (Rear A/C Control Head (Climatronic) -E265-).
- Use address word "08" or "28" to select "Air conditioner/heater electronics" or "Rear air conditioner operating element".
- Open vents in passenger compartment (in instrument panel, center console and B-pillars).
- Check DTC memory. With Manufacturer Scan Tool







Indicated on display of VAS 5051:
- Select function "03 - Output Diagnostic Test Mode (DTM)".

Indicated on display of VAS 5051:







- Display zone -1- shows which control element is currently being actuated (e.g. 1st control element in test).
- Display zone -2- gives a consecutive list of control elements already actuated and the one currently being actuated. The one currently being actuated appears in the bottom line.

- Touching the key selects the next component. For operation and sequence, refer to Table of control elements actuated.

NOTE:
- Return to selection program by touching <- key.
- Output Diagnostic Test Mode (DTM) can be terminated by pressing C-key.
- On completion of output Diagnostic Test Mode (DTM), check DTC memory. With Manufacturer Scan Tool
- If output Diagnostic Test Mode (DTM) is aborted, check DTC memory and read measured value block (e.g. display group 002 for Climatronic Control Module -J255-).
With Manufacturer Scan Tool
Reading