DTC Memory, Checking and Erasing
Requirements- All fuses OK as per wiring diagram
- Ambient (outside) temperature greater than 10 °C (50 °F), test drive vehicle for at least 5 minutes with A/C switched on.
- Engine speed (RPM) must be increased above idle
NOTE: Do not switch engine OFF after test drive or DTC memory will be erased.
- Leave engine running after test drive. DO NOT switch engine off. Leave A/C switched ON.
- Using VAG 1551/1 adaptor cable, connect VAG 1551 Scan Tool (ST) to Data Link Connectors (DLC) as follows:
- Remove cover from auxiliary relay panel I in plenum.
- Connect black connector to black DLC (battery positive voltage (B+) supply to DLC).
- Connect white connector to white DLC.
Blue connector is not used.
NOTE If there is no display on VAG 1551, check B+ supply to black DLC.
Indicated on display 1)
V.A.G - On Board Diagnostic HELP
1 - Rapid data transfer
2 - Blink code output
1) Operating modes -1- and -2- appear alternately
NOTE:
- Press the HELP button to obtain additional operating information.
- Press the -> button to step through program sequence.
- Switch printer ON with print button (button lights up).
- Press button -1- to select "Rapid data transfer" operating mode 1.
Indicated on display
Rapid data transfer HELP
Input address word XX
- Press buttons -0- and -8- to select "AC/Heating Electronics" address word 08.
Indicated on display
Rapid data transfer Q
08 - AC/Heating Electronic
- Press -Q- button to confirm input.
Control module identification and coding are displayed
4A0919579 AX Ctl. Air cond. XXX DX ->
Display on VAG 1551 Engine
4A0 919 579A Ctl. Air Cond 6-cyl. 6-cyl. - gasoline
NOTE:
- Display "DXX" indicates software version of A/C clutch control module -J153- and has no meaning for OBD.
- See current parts catalog for proper application of control module.
- If the control module code does not correspond to vehicle engine, replace A/C compressor clutch control module
If display appears as shown:
Rapid data transfer HELP
Control module does not answer
Rapid data transfer HELP
K wire not switching to Ground
Rapid data transfer HELP
K wire not switching to B+
- Press HELP button to print out list of possible causes.
- Check wire connections of DLC.
- Using wiring diagram, check B+ supply to A/C clutch control module -J153- terminals 30 and 75, then check Ground (GND) connection for open circuit.
- After repairing possible malfunctions, press -0- and -8- buttons to select "AC/Heating Electronics" address word 08.
- Press -Q- button to confirm input.
If display appears as shown
Malfunction in communication set-up
- Check wire connections of DLC.
- Press -> button.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -2- to select the "Check DTC Memory" function 02.
Indicated on display
Rapid data transfer Q
02 - Check DTC Memory
- Press -Q- button to confirm input.
Number of stored malfunctions or "No malfunctions recognized" is displayed
X malfunctions recognized! ->
- Press -> button.
Stored malfunctions (if any) are displayed and printed out one after another.
No malfunctions recognized! ->
- Press -> button (after last malfunction has been displayed and printed).
Indicated on display
Rapid data transfer HELP
Select function XX
- Switch ignition OFF.
- Eliminate/repair any faults.
NOTE: DTC memory is erased when ignition is switched OFF
If A/C compressor clutch does not engage even though no malfunction was recognized:
- Read measuring value block.
- Perform output DTM.