Data Link Connectors, Checking Wiring

Data Link Connectors (DLC), checking wiring

Notes:

^ The DLCs and the wiring connections "K" and "L", for all vehicle systems with On Board Diagnostic (OBD) are located in relay carrier (in plenum chamber, left).

^ For wiring colors and details of other vehicle systems connected to the "white" DLC see Wiring Diagrams.

^ For testing, use digital multimeter Fluke 83 (US 1119), auxiliary test set VAG 1594 and test box VAG 1598 with adapter harness VAG 1593/3.

- Switch off ignition before testing wiring connections.

DLC's In Fuse Panel:

Black DLC
(Power supply)

^ Terminal -1- (connected to Ground)

^ Terminal -2- (B+, connected to terminal - 30 via fuse 21).

White DLC
(Data transmission)

^ Terminal -1-
is not required for brake electronics.

^ Terminal -2-
Data line for "Rapid data transfer". The wiring from the DLC goes via wiring connection "K" to the ABS Control Module - J104 (terminal - 31 See Wiring Diagram).

Notes:

ABS ECM Connector - 35 Pin:

- Disconnect wiring connector from ABS Control Module - J1O4 (See Repair Group 45), connect test box VAG 1598 with adapter harness VAG 1598/3 and take test readings at appropriate sockets of test box (See Wiring Diagram).

- Use digital multimeter Fluke 83 (US 1119) to check for open circuit or short circuit to positive or Ground.

Checking wiring connections when VAG 1551 indicates "Fault In communication buildup"

- Isolate the wiring of the other vehicle systems with OBD ("Rapid data transfer") from the "white" DLC, terminal -2- by disconnecting them one by one from the wiring connection "K" (in relay station 1).

Note:
Refer to "Wiring Diagrams" for details of other systems with OBD function.

- Enter the address code "03" in operating mode "Rapid data transfer" again after the wiring for each of the other vehicle systems has been isolated.

- if the Scan Tool then shows the Control Module identification, check the wiring going to the Control Module that was disconnected last, using the Wiring Diagram. If no malfunction is found in the wiring, replace the Control Module that was disconnected last and reconnect all wiring connections.

Note:
If the Scan Tool indicates "Control Module does not answer", this means that the wiring to the Control Module - J104 has now also been disconnected.