Scan Tool Testing and Procedures
PURPOSEOutput Diagnostic Test Mode (DTM) is provided to check the mechanical motion and the electrical wiring of certain actuators.
DESCRIPTION
The actuators are checked acoustically or by touch. In some cases, it might be necessary to use an LED tester for the fuel injectors, as the clicking sound from the injectors is very soft and short. Avoid background noise during audible check of the injectors.
When an audible "click" is heard from the actuator being tested, this only confirms that there is electrical current to the actuator and that the component is operating mechanically. The audible noise does not guarantee perfect component operation. Additional testing may be necessary.
This function can only be carried out with the engine OFF (not running) and the ignition switch turned ON. The ignition switch should remain ON throughout entire test. The DTM will be interrupted if the engine is started or if an engine speed pulse is detected.
When performing Output Diagnostic Test Mode, the last DTM that was displayed will be stored in the Engine Control Module (ECM) and that display will be the first to appear the next time this mode is activated. It does not automatically go to the beginning of the sequence.
The following components are activated by the Output DTM in the sequence given:
1. Cylinder 1 Fuel Injector (N30)
2. Cylinder 3 Fuel Injector (N32)
3. Cylinder 4 Fuel Injector (N33)
4. Cylinder 2 Fuel Injector (N31)
5. Idle Air Control (IAC) valve (N71)
6. Evaporative Emissions (EVAP) Canister Purge Regulator valve (N80)
7. Heated Oxygen Sensor (HO2S) Relay (J278)
8. EGR Vacuum Regulator Solenoid valve (N18) (two-way valve)
9. DISREGARD DISPLAY, NOT APPLICABLE
REQUIREMENTS
- Battery Positive Voltage (B+) OK.
- Fuse no. 22 (S22) OK.
- Ground (GND) connections for engine and transmission which are located on the upper intake manifold support to lower part of intake manifold, are OK.
VAG 1551 CONNECTING
For access to the Data Link Connector:
- Remove front ashtray.
- Slide small cover to the left (arrow).
- With ignition switched off, connect VAG 1551/3 adapter harness between Data Link Connector and VAG 1551 Scan Tool.
^ Indicated on display:
VAG ON BOARD DIAGNOSTIC HELP
1-Rapid data transfer
2-Blink Code Output
NOTE:
- Operating modes 1 and 2 are displayed alternately.
- If no display appears, do not connect the white connector. In this case, check the voltage supply for the VAG 1551 Scan Tool.
- Connect white connector from VAG 1551/1 adapter harness to white Data Link Connector (blue connector is not used).
- Switch ignition ON.
- Operate the VAG 1551 Scan Tool while observing display.
- Press PRINT button.
- Press button -1- for "Rapid data transfer" operating mode.
- Press buttons -0- and -1- to enter address word 01 for "Engine Electronics".
- Press -Q- button to confirm input.
- Press --> button.
- Press buttons -0- and -2- for "Check DTC Memory" function.
- Press -Q- button to confirm input.
- Press buttons -0- and -5- for "Erase DTC Memory" function.
- Press -Q- button to confirm input.
- Press --> button.
- Press buttons -0- and -3- for "Output Diagnostic Test Mode" function.
^ Indicated on display:
Rapid data transfer Q
03 - Output Diagnostic Test Mode
ACTIVATING CYLINDER # 1 FUEL INJECTOR
- Press -Q- button to confirm input.
^ Indicated on display:
Output Diagnostic Test Mode -->
Injector, Cyl. 1 - N30
- If anything else appears in the display, press the --> button until "Select function XX" appears.
- Press buttons -0- and -3- to enter the "Output Diagnostic Test Mode" function again.
- Press -Q- button to confirm input.
- Open throttle and close.
- Cylinder 1 Fuel Injector (N30) must click.
NOTE: The Fuel Injectors click very softly. Avoid other sources of noise in the vicinity when checking.
- Open and close throttle again.
- Press --> button.
- If one or more of the valves does not click, perform electrical testing, Test Steps 12 - 15. Refer to Diagnostic Charts / Trouble Code Charts. Related Tests, Information and Procedures
- If necessary, replace Motronic Engine Control Module.
ACTIVATING IDLE AIR CONTROL VALVE
- Skip the individual checks for fuel injectors # 3, # 4 and # 2.
- Press --> button repeatedly until next display appears.
^ Indicated on display:
Output Diagnostic Test Mode
Idle Air Control Valve - N71
NOTE:
- The IAC Valve must pulsate (noticeably) until the next test in the DTM sequence is selected by pressing the --> button.
- If the Fuel Injectors, Solenoid Valve 1 for EVAP Canister Purge Regulator Valve or EGR Vacuum Regulator Solenoid Valve are faulty, or the wiring to these components is faulty, the IAC Valve will only pulsate if the ignition is not switched off after erasing the Diagnostic Trouble Code (DTC) Memory.
- If the IAC Valve does not pulsate, perform electrical testing, Test Step 25. Refer to Diagnostic Charts / Trouble Code Charts. Related Tests, Information and Procedures
- If necessary, replace Motronic Engine Control Module.
ACTIVATING EVAP CANISTER PURGE REGULATOR VALVE
- Press --> button.
^ Indicated on display:
Output Diagnostic Test Mode -->
EVAP Canister Purge Regulator Valve - N80
NOTE: The solenoid (on the Air Cleaner Housing) must click until the next test in the DTM sequence is selected by pressing the --> button.
- If the valve solenoid does not click:
- Disconnect connector -1- from valve -2- and connect US 1115 LED tester to the disconnected connector with adapter leads from VW 1594 adapter kit.
NOTE: The LED must blink.
- If LED blinks:
- Replace solenoid.
- If LED does not blink:
- Switch ignition OFF.
- Reconnect connector to EVAP Canister Purge Regulator Valve.
- Perform electrical testing, Test Step 16. Refer to Diagnostic Charts / Trouble Code Charts. Related Tests, Information and Procedures
- If necessary, replace Motronic Engine Control Module.
ACTIVATING HEATED OXYGEN SENSOR RELAY
- Press --> button.
^ Indicated on display:
Output Diagnostic Test Mode -->
Heated Oxygen Sensor Relay - J278
NOTE: HO2S Relay (on auxiliary fuse/relay panel) must click until the next test in the DTM sequence is selected by pressing the --> button.
- If relay does not click:
- Check electrical wiring according to wiring diagram.
ACTIVATING EGR VACUUM REGULATOR SOLENOID VALVE
- Press --> button.
^ Indicated on display:
Output Diagnostic Test Mode -->
EGR Vacuum Regulator Solenoid Valve - N18
NOTE: EGR Vacuum Regulator Solenoid Valve must click until the next test in the DTM sequence is selected by pressing the --> button..
- If the valve does not click:
- Disconnect connector -1- from valve -2- and connect VAG 1527 LED tester to the disconnected connector with adapter cable from VW 1594.
NOTE: The LED must blink.
- If LED blinks:
- Replace EGR Vacuum Regulator Solenoid Valve.
- If LED does not blink:
- Switch ignition OFF.
- Reconnect connector to the Solenoid Valve.
- Perform electrical testing, Test Step 29. Refer to Diagnostic Charts / Trouble Code Charts. Related Tests, Information and Procedures
- If necessary, replace Motronic Engine Control Module.
- Press --> button.
^ Indicated on display:
Output Diagnostic Test Mode
Intake Manifold Change-over Valve - N156
- Disregard display.
- Press --> button.
- Press buttons -0- and -6- to select the "End Output" function.
- Press Q button to confirm input.