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Interrogating fault memory > < Performing the self-diagnosis

A4 Mk1

Heating, Air Conditioner
Performing the self-diagnosis
connecting fault reader V.A.G 1551 and selecting functions

Test requirements:

  • ● Supply voltage of vehicle electrical system OK
  • ● Fuses OK.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder
 
A24-0028
  • ‒ → Open rear ashtray (in centre console) and remove cover for diagnostic connection.
 
A24-0029
  • ‒ → Connect fault reader V.A.G 1551 with lead V.A.G 1551/3 (ignition switched off).
 
→ Indicated on display:
V.A.G SELF DIAGNOSIS     HELP
1 - Rapid data transfer 1)
2 - Flash code output 1)

    1)    appears alternately

Note:

If the display remains blank, use the current flow diagram to check the power supply and wiring.

Depending on which function is required => "Available functions" table, Page 01-7:

  • ‒ Switch the ignition on.
  • or
  • ‒ Start the engine.
  • ‒ Set the operating mode "Auto" on the operating and display unit -E87 (compressor running).
  • ‒ Press the PRINT key to switch on the printer - (indicator lamp in key lights up).
  • ‒ Enter "1" to select "Rapid data transfer".
 
→ Indicated on display
Rapid data transfer    HELP
Enter address word XX

Note:

Address word 00 implements the automatic test sequence, i.e. the interrogation of the fault memory via rapid data transfer for all vehicle systems with a self-diagnosis capability.

  • ‒ Enter "08" for the address word "Air conditioner/heating electronics".

Note:

With the operating and display unit -E87 with Part No. 8D0 820 043, index "C", the air conditioner control is now switched off.
 
→ Indicated on display
Rapid data transfer    Q
08 AC/heating electronics
  • ‒ Confirm entry with Q key.
 
→ Indicated on display
Rapid data transfer
Tester sends address word 08
  • ‒ Wait until the next display appears.
 
→ The display on the fault reader V.A.G 1551 will show the control unit identification code (example).
8D0820043X A4 Fully automatic air conditioner    DXX ⇒
Coding XXXXX    WSC XXXXX

Note:

You may print out the control unit identification by pressing the PRINT key on the fault reader V.A.G 1551.

Control unit identification (example)

- 8D0 820 043 X
- or
- 8L0 820 043 X

Part-No.; assignment
=> Parts List

- A4 Fully automatic air conditioner

Audi A4 control unit for fully automatic air conditioner

- DXX

Control unit data status (software type)

- Code XXXXX:

Different codings

- WSC XXXXX:

Workshop Code for the V.A.G 1551 which was used to perform the last encoding
  • ‒ Press ⇒key.
 
→ Display function selection):
Rapid data transfer    HELP
Select function XX

Notes:

  • ◆ The control unit identification can be displayed again by entering function "01" for "Interrogating control unit version" and confirming with the Q key.
 
→ Indicated on display
Rapid data transfer    HELP
No reply from control unit
  • ‒ Print out possible cause of trouble by pressing HELP key.
 
Use the current flow diagram to check the wiring for the diagnostic connector.
Rapid data transfer    HELP
K-wire not switched to positive
 
Rapid data transfer    ⇒
No signal from control unit
 
→ If this display appears at the start of or during the program, faults have occurred and data exchange is no longer possible between the fault reader V.A.G 1551 and the operating and display unit -E87.
Rapid data transfer    ⇒
Communication problem
  • ‒ Use the current flow diagram to check the wiring for the diagnostic connector.
  • ‒ After rectifying the possible causes of the fault, re-enter "08" for the address word "Air conditioner/heating electronics" => Page 01-11.

Interrogating fault memory > < Performing the self-diagnosis