Output Diagnostic Test Mode (DTM) (Function 03)

Output Diagnostic Test Mode (DTM) (Scan Tool Function 03)


NOTE:
- Output DTM must only be carried out with the engine not running.
- For definitive results, output DTM must be carried out at an ambient temperature of at least 12 °C (54 °F) as displayed on A/C control head.
- During output DTM, both coolant fans (-V7- and -V35-) are activated.
- Climatronic does not function or automatically regulate during output DTM.
- Output DTM can be repeated several time, If necessary.


Initiating Output DTM
- Connect VAG 1551 Scan Tool (ST) and select AC/Heating electronics (address word 08). Scan Tool Connecting and Initial Checks

Indicated on display (function selection):


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -3- to select "Output Diagnostic Test Mode" function 03.

Indicated on display


Rapid data transfer Q
03 - Output diagnostic test mode


- Press Q button to confirm input.

Indicated on display


Output diagnostic test mode


The following functional tests are carried out in sequence:
- A/C Control head -E87- display
- Flap motors
- Electrical circuit to (the following) blower motors:
Fresh air blower -V2-
Rear evaporator fan -V20-
Rear warm air fan -V47-
- Electrical circuit to A/C clutch -N25-

Indicated on display


Function is not recognized or cannot ->
be carried out at the moment!


- Output DTM is concluded.
- Press -> button.


NOTE: After completing output DTM, always check DTC memory again and rectify any malfunctions that may have been recognized during output DTM.


A/C Control head -E87- display test

Vehicles > 9.98







Vehicles 09.98 >







For both versions, all display segments must appear fully in display. If not, replace -E87-.

Flap motor test

During output DTM:
- Temperature regulator flap motor-V68-
- Central air flap motor -V70-
- Foot well/defrost flap motor -V85- are activated in sequence and move over their complete operating range. The first half of the motor movement range will be continuously activated, the remainder will be driven in stages.

The movement will be completed in approx. 30 seconds and the flap motor adopts the position selected on the A/C control head.


NOTE: If after subsequent checking of DTC memory, no DTC is recognized (even though the selected positions were not attained), check the appropriate flap motor or air flap for mechanical damage.


Electrical circuit tests

Blower/fan motors

During output DTM, the following are activated in sequence with 2 different voltages:
- Fresh air blower -V2-
- Rear evaporator fan -V20-
- Rear warm air fan -V47-

Should a malfunction be detected in the electrical circuit to one of the motors listed, it will be stored in DTC memory.

A/C clutch -N25-

During output DTM, the electrical circuit is tested from connectorT28b/14 via A/C evaporator temperature switch -E33- to after A/C pressure switch -F129-. Should a malfunction be detected, it will be stored in the DTC memory.


NOTE: If after subsequent checking of DTC memory, no DTC is detected (even though the A/C clutch is NOT activated during cooling operation), then check wiring and connections from A/C pressure switch -F729- via -F763- and -J32- to A/C clutch -N25- using wiring diagram.