Testing wiring of diagnostic connector — AUDI

The diagnostic connectors and junctions "K" and "L" for all on-board systems with self-diagnosis are grouped in relay point 1 in the plenum chamber (left side). For wiring colours and other on-board systems connected to "white" diagnostic connector:

=> Current flow diagrams, Electrical fault finding and Fitting locations

Switch off the ignition before testing the wiring connections.
Use hand-held multimeter V.A.G 1526, auxiliary test set V.A.G 1594 and test box V.A.G 1598/20 for testing.

Testing voltage supply for fault reader V.A.G 1551, "black" diagnostic connector:

Contact 1 connected to battery earth.
Contact 2 connected to positive

Test wiring.

=> Current flow diagrams, Electrical fault finding and Fitting locations

Testing diagnostic wiring "L" and "K"; "white" diagnostic connector:

Contact 1, diagnosis wire "L", is not used for ABS, ABS/EDL or ASR systems

Contact 2, diagnostic wire "K" for"Rapid data transfer". The link with the control unit is set up and data are exchanged via the "K" wire. The "K" wire is routed from the "white" diagnostic connector via the junction "K" to the various control units.

Connect test box V.A.G 1598/20 to connector of control unit -J104=>Page
01-206
.
Test for open circuit in wiring between socket 46 of test box and contact 2 of diagnostic connector. It is not normally possible to trace a short to earth or short to positive.At junction "K", disconnect the wiring to all on-board systems with self-diagnosis ("Rapid data transfer") in turn. Test the corresponding "K" wires.

=> Current flow diagrams, Electrical fault finding and Fitting locations

Test the wiring connection to the control unit which was last disconnectedaccording tocurrent flow diagram

=> Current flow diagrams, Electrical fault finding and Fitting locations

If no fault is found in the wiring and the supply voltage at the control unit is OK (not less than 10.5 V), renew the control unit.

"Blue" diagnostic connector is not used for operating mode "Rapid data transfer".

Testing wiring connection if V.A.G 1551 indicates "Fault in communication build-up":

If the display on V.A.G 1551 indicates "Fault in communication build-up", the fault may be in control unit -J104 or in other control units which are not relevant for the ABS, ABS/EDL or ASR system, but which prevent the diagnostic link from being established.

At junction "K", disconnect the wiring between contact 2 of the "white" diagnostic connector and all on-board systems with self-diagnosis ("Rapid data transfer") in turn.

Note:

Other systems with self-diagnosis:

=> Current flow diagrams, Electrical fault finding and Fitting locations

After disconnecting each of the on-boardsystems, select address word "03" in operating mode "Rapid data transfer" once again.
If the display then shows the control unit identification of control unit -J104, renew the control unit which was last disconnected and reconnect all wiring connections.

Note:

If the display shows "Control unit does not answer", there is an open circuit in the wiring connection to control unit -J104.