Output Diagnostic Test Mode (DTM) (Function 03)
Performing Output Diagnostic Test Mode
The Output diagnostic test mode activates the following components in the following sequence:
1. Cold Start Injector -N108-
2. EGR Vacuum Regulator Solenoid Valve -N18-
3. Air Conditioning compressor interrupt
4. Fuel Cut-off Valve -N109-
5. Wastegate Bypass Regulator Valve -N75- for boost control
6. Glow Plug Relay -J52-
7. Glow Plug Indicator Lamp -K29-
8. Relay -J359- preheat coolant, low heat output (man. trans. only)
9. Relay -J360- preheat coolant, high heat output (man. trans. only)
10. Malfunction Indicator Lamp (MIL) -K82-, Exhaust Warning Lamp -K83- (MIL is shown in the 1551 display, however; -K83- Exhaust Warning Lamp is the actual component being tested)
Special tools and equipment
- Scan Tool (ST) V.A.G 1551 or VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/22 (through my 1999)
- Test box VAG 1598/31 (from my 2000)
- Adapter set VAG 1594
- Digital multimeter US 1119 (Fluke 83 or equivalent)
- Diode test lamp VAG 1527
- Adapter set VAG 1594
- Wiring diagram
Test conditions
- Main fuses OK.
- Fuses No.29, 32, 34 and 43 OK.
Prerequisites (with air conditioning)
- Vehicle at room temperature, warmer than +15 °C (59 °F)
- A/C on
- Lowest temperature setting and highest blower speed
NOTE:
- Activation of individual control elements is limited to 30 secs. but can be stopped at any time by pressing -> button.
- Final controls are checked acoustically or by touching.
- Ignition must be switched off before repeating Output Diagnostic Test Mode.
Work sequence
- Connect Scan Tool (ST) V.A.G 1551/(VAG 1552).
- With engine idling, select Engine Control Module (ECM) with "Address word" 01 (Connecting Scan Tool (ST) and selecting ECM) [1][2][3][4]Reading and Clearing Diagnostic Trouble Codes
Indicated on display:
Rapid data transfer HELP
Select function XX
- Operate Scan Tool (ST) and advance through program sequence by following display.
- Press buttons -0- and -3- for "Output Diagnostic Test Mode" (DTM).
Activating Cold Start Injector -N108-:
Indicated on display:
Rapid data transfer Q
03 Output Diagnostic Test Mode (DTM)
- Press -Q- button to enter input.
Indicated on display:
Output Diagnostic Test Mode (DTM) ->
Cold Start Injector -N108-
NOTE: Activating Cold Start Injector -N108- influences pre-ignition (noise).
If no change in combustion noise is heard:
- Check injection timing control range
Activating EGR Vacuum Regulator Solenoid valve -N18-:
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
Exhaust Gas Regulator valve -N18
Valve must click.
NOTE: It is difficult to hear the valve click due to engine noise. Determine valve operation by feel (touch).
Valve does not click:
- Check EGR Vacuum Regulator Solenoid Valve -N18-
Activating air conditioning compressor interrupt:
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
A/C Compressor interrupt
- Air conditioner compressor shut-off is checked.
- Test step is also called up on vehicles without A/C.
- A/C compressor must stop within 5 secs. (visual check) then start approx. every 5 secs. and then stop.
If A/C compressor does not switch off:
- Check signals from/to A/C, refer to "A/C System Signals, Checking".
Activating Fuel Cut-off Valve -N109-:
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
Fuel Cut-off Valve -N109-
- Engine must stop.
If engine does not stop:
- Switch off ignition.
- Remove Fuel Cut-off Valve -N109- and remove any metal chips or dirt.
- Repeat Output Diagnostic Test Mode, if engine will not stop replace Fuel Cut-off Valve -N109-.
If engine stops:
- Continue Output Diagnostic Test Mode with engine stopped and ignition on.
Activating Wastegate Bypass Regulator valve -N75-:
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
Wastegate Bypass Regulator Valve -N75-
The solenoid valve must operate and the rod for the charge pressure control pressure unit on the turbocharger must move back and forth (at least 3 - 4 times, as long as there is vacuum in the vacuum reservoir).
If the solenoid valve does not operate:
- Check charge pressure control solenoid valve -N75-
Activate Glow Plug Relay -J52-:
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
Glow Plug Relay J52
Relay must click.
Switching relay on and off can also be observed by the brightening and dimming of the interior light as a result of glow plug power consumption.
If relay does not click:
- Check glow plug relay.
Activate Glow Plug Indicator Lamp -K29-:
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
Glow Plug Indicator Lamp -K29-
Glow Plug Indicator Light -K29- must blink.
Glow Plug Indicator Light -K29- does not blink:
- Check Glow Plug Indicator Lamp -K29-.
Activating Relay for low heat output -J359- (only on vehicles with manual transmission):
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
Low heater output relay -J359-
Relay must click.
If relay does not click:
- Check low heat output relay:
Activating Relay for high heat output -J360- (vehicles with manual transmission):
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
High heat output relay -J360-
Relay must click.
If relay does not click:
- Check relay for preheating coolant, high heat output -J360-.
Activating Malfunction Indicator Lamp (MIL) and Switch -K82-:
- Press -> button.
Indicated on display:
Output Diagnostic Test Mode ->
Malfunction Indicator Lamp (MIL)
MIL must flash.
MIL does not flash:
- Check Malfunction Indicator Lamp (MIL) and Switch -K82-:
- Press -> button.
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -6- for "End output" and confirm with -Q- button.
- Switch off ignition.