Testing wiring between white diagnostic connector and engine control unit — AUDI

Note:

This check has to be performed if one of the following displays appears on the connected fault reader V.A.G 1551.

Rapid data transfer
Communication problem
Display:

or

Rapid data transfer
HELP
K wire not switching to earth

or

Rapid data transfer
HELP
K wire not switched to positive

or

Rapid data transfer
HELP
L wire not switching to earth

or

Rapid data transfer
HELP
L wire not switching to positive

The wiring between the white diagnostic connector and engine control unit is routed via junctions K and L.

Installation position of diagnostic sockets: In auxiliary relay carrier I in the left plenum chamber

Notes:

If wires of different colours are connected to junction K, determine the wire colour:

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

If wires of the same colour are connected to wiring junction K, determine wire assignment using test box V.A.G 1598 A (resistance measurement).

In this case proceed as follows for the fault finding:

One by one, disconnect the wire connections of the other vehicle systems with self-diagnosis from junction K.

After connector to specific vehicle system has been detached, enter address word "01" again for engine electronics after switching on ignition.

If engine control unit identification is displayed:

After switching on the ignition enter address word "00" for automatic test sequence to determine to which control unit the disconnect wires belong.
Check or replace diagnostic wiring of disconnected control unit.

If the control unit identification is again not displayed:

Remove engine control unit => Page
25-12
.
With the ignition switched off, use adapter V.A.G 1598/3 to connect test box V.A.G 1598 A to plug connection of engine control unit (control unit remains disconnected) => Page
25-9
.

Check for open circuit and short to earth/positive or earth in the following wiring connections:

White diagnosisconnector / Contact · Wiringjunction · Test box V.A.G 1598 A / Bushing
1 · L · 22
2 · K · 1

Rectify any open/short circuit as necessary.

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

Note:

Proceed in the same way to test the L wire.