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Selecting functions > < Basic notes on self-diagnosis

A4 Mk1 ABS and ESP Self-Diagnosis with VAG 1551

Running Gear Self-diagnosis for ABS, ESP
Self-diagnosis
Connecting fault reader V.A.G 1551 and selecting address word
 
A24-0028

Use can be made of the vehicle diagnostic system tester V.A.G 1552 or the vehicle diagnostic, testing and information system VAS 5051 instead of the fault reader V.A.G 1551. However, with vehicle systems tester V.A.G 1552 there is no option to print out information.

  • ● Observe the test requirements for the system concerned.
  • ‒ → Open rear ashtray.
 
A24-0029
  • ‒ Remove the cover for the diagnostic connector.
  • ‒ → With the ignition off, connect fault reader to diagnostic connector using wire V.A.G 1551/3.
 
→ Indicated on display:
V.A.G self diagnosis    HELP
1 - Rapid data transfer 1)
2 - Flash code output 1.

1) displayed alternately

Notes:

  • ◆ Check the connections of the diagnostic connector if there is no display on the screen.
 
A24-0029

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

  • ◆ The PRINT key is used to switch on the printer. When the printer is on the warning lamp in the print key illuminates.
  • ◆ Depending on the program, additional operating information can be printed out by pressing the HELP key of V.A.G 1551.
  • ‒ Switch the ignition on.
  • ‒ Switch on the printer by pressing the Print key on the fault reader.
  • ‒ Press key -1- for "Rapid data transfer" operating mode.
 
→ Indicated on display:
Rapid data transfer     HELP
Enter address word XX

Note:

The address word selects the control unit of the on-board system that you wish to test with the fault reader. The address word is made up of two digits, which are given in the relevant sections of this Workshop Manual.

For example: Press keys 03 to enter the address word for "Brake electronics".
 
→ Indicated on display:
Rapid data transfer     Q
03 - Brake electronics
  • ‒ Confirm input with Q key.
 
→ Display after address word 03 has been entered:
Rapid data transfer
Tester sends address word 03

Note:

If a fault occurs in the communication link between fault reader V.A.G 1551 and the control unit, one of the following four displays will appear.
 
Press the HELP key to obtain a printout of the possible causes of fault.
K-wire not switching to earth/positive
    HELP
 
Check diagnostic wiring ("K" wire).
No signal from control unit

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

  • ‒ Check voltage supply and earth connection to control unit -J104.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder
 
→ If this display appears:
Communication problem
  • ‒ Rectify fault

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

  • ‒ After rectifying possible causes of fault, enter address word 03 for brake electronics once again and confirm with Q.
 
→ If communication between fault reader and control unit has been established and is functioning properly, display indicates control unit -identification (X), system designation (Y), hardware and software version (Z), coding (V) and workshop code (W).
XXX XXX XXX    YYY YYY YY YY YY     ZZZ    ⇒
Coding VVVVV    WSC WWWWW

Notes:

  • ◆ The ⇒ key is used for the continuation of the program sequence.
  • ◆ The various on-board systems to be tested are described in more detail in the relevant sections of this Workshop Manual.
  • ◆ The control unit index can only be changed by fitting a new control unit

=> Replacement Parts Catalogue

  • ◆ If the control unit identification number does not appear in the display then check the diagnostic wiring.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

  • ‒ Press ⇒key.
 
→ Indicated on display:
Rapid data transfer     HELP
Select function XX

Selecting functions > < Basic notes on self-diagnosis