Notes

Electrical testing
Special tools and equipment





^ VAG1598/21 adapter
^ VW1594A connector test kit
^ Multimeter (Fluke 83 or equivalent)
^ VAG 1921 pliers

^ If On Board Diagnostic (OBD) does not give any indication of the source of the malfunction, carry out all of the electrical test steps.
^ If On Board Diagnostic (OBD) provides a direct indication of the source of the malfunction, only carry out the test steps recommended in the DTC table (specific testing).

An overview of all the test steps in the Electrical test table can be found.

Test Requirements
^ Ignition and electrical consumers switched off before beginning the check (headlights, lighting, fan, etc.)
^ Fuses -S9-, -S13-, -S20-, -S178-, -S179must be OK (remove fuses from fuse holder to check)

Removing air cleaner





^ Pull harness connector -2- off Mass Air Flow (MAF) sensor.
^ Release spring-type clip on air duct hose -1- using VAG 1921 pliers and pull hose off air cleaner.
^ Remove air cleaner bolts -3- -4- and take out air cleaner .





^ Release control module harness connector (arrow -1-) and pull off (arrow -2-).





^ Pull multi-pin harness connector off ABS control module -J104- and connect VAG 1598/21 test box (-1-) to harness connector -2-.

The specified values are matched to the multimeter (Fluke 83 or equivalent) and are not necessarily applicable for other test units.

Multi-pin harness connector with terminal assignment

Note:
All Terminals not listed are currently not assigned and must never be connected to other components!





Data Link Connector (DLC) for voltage supply and On Board Diagnostic (OBD) with VAG1551 Scan Tool (ST) terminal assignment.

Terminal 4 = Ground (terminal 31)
Terminal 16 = Positive (terminal 30) via- S12
Terminal 7 = K-wire via connection in instrument panel wiring harness to ABS control module -J104- terminal 7.





T25 harness connector and ABS control module -J104- terminal assignment.





CAN-bus control diagram
1. Automatic Transmission Control Module (TCM)
2. Bus driver
3. ECM
4. Bus-driver
5. Terminating impedance
6. CAN-bus
7. Terminating impedance
8. Bus driver
9. ABS control module -J104-





Terminal Description 1 thru 7





Terminal Description 8 thru 15





Terminal Description 16 thru 25





Test Step Overview Part 1 of 3





Test Step Overview Part 2 of 3





Test Step Overview Part 3 of 3

Electrical test table

Notes:
^ The socket designations of adapter VAG1598121 are identical to ABS control module -J104- terminal designations.
^ If the readings obtained deviate from the specifications, carry out "corrective action" measures in the right side of the table
^ Use only the VW1594A connector test kit to check continuity (bridging).
^ If the measured figures only differ slightly from the specifications, clean the sockets and harness connectors of the testers and adapter leads (using contact spray G 000 700 04 ) and repeat the check. Before replacing components, check the wiring and connections again, particularly if the specification calls for a resistance reading of less than 10 Ohms.