Checking VAG1551/1 Data Link Connector (DLC) Wiring

VAG1551/1 Adapter
Connector Plug -A- (Black)
Terminal No. 1 to Scan tool connector -D- terminal No. 3 GND (-)
Terminal No. 2 to Scan tool connector -D- terminal No. 2 Battery (B+)
Connector Plug -B- (White)
Terminal No. 1 to Scan tool connector -D- terminal No. 4 L Wire
Terminal No. 2 to Scan tool connector -D- terminal No. 1 K Wire
Connector Plug -C- (Blue)
Terminal No. 1 to Scan tool connector -D- terminal No. 5 Lamp Wire (not used





NOTE:
^ DLCs, K-wires and L-wires for all On Board Diagnostic (OBD) systems are located in the auxiliary relay panel 1 (in plenum, left side), refer to Wiring Diagrams.
^ For wire colors and other details for systems connected to the white DLC, refer to Wiring Diagrams.
^ For testing, use digital multimeter (Fluke 83 or equivalent), VW1594 or equivalent connector test kit, and VAG1598 or equivalent test box with VAG 1598/03 or equivalent adapter
^ Switch ignition off before testing wiring connections.





Black DLC (power supply)
- Terminal -1-: Ground
- Terminal -2-: B+ (terminal 30) via fuse 21 (-S21-)





White DLC (data transfer)
- Terminal -1-: not required for brake electronics
- Terminal -2-: data line for "Rapid data transfer"
- DLC wiring is routed via the K-wire to the ABS control module -J104- (connector terminal 31, refer to wiring diagram).






NOTE:
^ Disconnect the ABS control module harness connector, connect VAG1598 or equivalent test box with VAG1598/03 or equivalent adapter, and make tests at the appropriate test box sockets, refer to wiring diagram.
^ Use digital multimeter (Fluke 83 or equivalent) to check for open circuits, short circuits to positive (+), or short circuits to Ground (-).