Output Diagnostic Test Mode (DTM), (Function 03)
Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
- VAG 1551/1552 Scan Tool with VAG 1551/3 adaptor cable
Vehicles with A/C, checking requirements:
- Vehicle at room temperature (warmer than + 15 °C)
- A/C system switched ON
- Select lowest temperature and highest blower speed
Output Diagnostic Test Mode (DTM) activates the following DTM components in the sequence given:
1. Cold start valve N108
2. EGR Vacuum Regulator solenoid valve N18
3. A/C compressor interrupt
4. Fuel cut-off valve N109
5. Wastegate Bypass Regulator valve N75
6 Glow plug relay J52
7. Glow Plug Indicator lamp K29
8. Low heater output relay J359
9. High heater output relay J360
10. Malfunction Indicator lamp (MIL)
(MIL is shown in the 1551 display however; the K83 exhaust warning lamp is the actual component being tested)
NOTES:
- Individual DTM component activation is limited to 30 secs. but can be stopped at any time by pressing the -> button.
- Ignition must be switched OFF before Output Diagnostic Test mode can be repeated.
Work Sequence
- Connect VAG 1551/1552 Scan Tool. [1][2]Reading and Clearing Diagnostic Trouble Codes
- Ensure that engine is running at idle
- Press 0 and 1 buttons to select Address word 01: "Engine Electronics"
Display will appear as shown
Rapid data transfer HELP
Select function XX
- Operate Scan Tool taking displayed information into account
- Press 0 and 3 buttons to select Function 03:"Output Diagnostic Test mode" (DTM)
Display will appear as shown
Rapid data transfer Q
03 Output Diagnostic Test Mode
- Press Q button to enter input
Display will appear as shown
Output Diagnostic Test Mode ->
Cold Start valve N108
NOTE: Activating the Cold start valve influences the sound of combustion considerably pre-ignition).
If no change in combustion sound is heard:
- Check injection adjuster control range. Testing and Inspection
- Press -> button.
Display will appear as shown
Output Diagnostic Test Mode ->
EGR Vacuum Regulator Solenoid valve N18
- Valve must click.
NOTES:
- Because of engine noise levels, valve click cannot be heard and therefore must be felt to detect its operation.
- Mechanical EGR valve piston movement is visible through the side slot.
If valve does not click:
- Check EGR system.
- Press -> button.
Display will appear as shown
Output Diagnostic Test Mode ->
A/C compressor interrupt on
NOTES:
- A/C compressor shutoff is checked.
- The test step is also recalled on vehicles without A/C.
- The A/C compressor must stop within 5 seconds (visual check) then start approx. every 5 seconds and then stop.
If A/C compressor not switched OFF
- Check signal from/to A/C system. A/C System Signals, Checking
- Press -> button.
Display will appear as shown
Output Diagnostic Test Mode ->
Fuel cut-off valve N109
- Engine must stop running.
If engine does not stop
- Switch OFF ignition.
- Unscrew Fuel cut-off valve and remove any foreign material.
- Repeat Output Diagnostic Test Mode
If engine will not stop
- Replace Fuel cut-off valve.
- Repeat Output Diagnostic Test Mode with engine NOT running and ignition switched ON.
- Press -> button until following display appears
Display will appear as shown
Output Diagnostic Test Mode ->
Wastegate Bypass Regulator valve N75
- N75 Valve must click.
NOTE: It is difficult to hear the valve click and is therefore best checked by touching.
If valve does not click
- Check Wastegate Bypass Regulator valve N75.
- Press -> button.
Display will appear as shown
Output Diagnostic Test ->
Glow plug relay J52
- Relay must click.
NOTE: Relay ON/OFF switching can also be detected by observing the interior light becoming brighter and darker as a result of the high glow plug power consumption.
If relay does not click
- Check glow plug relay
See Wiring Diagrams.
- Press->button.
Display will appear as shown
Output Diagnostic Test Mode ->
Glow Plug Indicator lamp K29
- Lamp must blink.
If lamp does not blink
- Check Glow Plug indicator lamp:
See Wiring Diagrams.
- Press -> button.
Display will appear as shown
Output Diagnostic Test Mode ->
Low heater output relay J359
- Relay must click.
If relay does not click
- Check low heater output relay:
See Wiring Diagrams.
- Press ->button.
Display Will appear as shown
Output Diagnostic Test Mode ->
High heater output relay J360
- Relay must click.
If relay does not click
- Check high heater output relay
See Wiring Diagrams.
- Press -> button.
Display will appear as shown, Display will appear as shown, NOTE that the display shows an MIL lamp; in reality, the K83 Exhaust warning lamp is being checked
Output Diagnostic Test Mode ->
Malfunction Indicator Lamp
- Malfunction Indicator lamp (Exhaust warning lamp K83) must light up
If NO
- Check K83 Exhaust warning lamp.
- Press -> button.
Display will appear as shown
Rapid data transfer HELP
Select function xx
- Press 0 and 6 buttons to select Function 06: "End transfer"
- Press Q button to enter input
- Switch OFF ignition.
This ends the Output Diagnostic Test Mode sequence.