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VAG-COM : Operation

Connectivity

The location for the on-board diagnostic (OBD) connectors in the S2 is usually the main fuse box under the bonnet. There is a 2-pin black coloured connector which supplies 12V to the diagnostic link, and a 2-pin white coloured connector conveying the 'K' and 'L' diagnostic signals to and from the OBD equipped control modules. Here's a (fuzzy) picture of the fusebox showing the OBD connectors - the close up lens is on order - Sorry !

On the earliest 3B engined S2 Coupes, the diagnostic plugs are located in the drivers-side front foot wheel, just below the parcel shelf, near the A-pillar. Believe this may only apply to 1991 cars. You do not need to remove any trim to locate these connectors on the early 3B Coupes. The 2-pin OBD plugs on the early S2 are also black and white. BTW - The white plug may be brown in some cars. Confused yet ?

In many cars, a blue coloured 2-pin connector may also be encountered, but this is ignored for VAG-COM use. It is used when pulling 'blink codes' from the ECU without a PC and VAG-COM software. More about 'blink codes' and that nifty blue connector here .

Note that the VAS5051-2 cable assembly which hooks into the VAG-COM adapter is physically keyed to only engage with the correct black and white (or brown) connectors on the vehicle. 

Activity

The ignition key needs to be at the engine running position for communications to be established with the car. The first thing to do is use the 'Test' option in the 'Options' screen of VAG-COM to verify that the software locates the ISO-COM adapter whilst the ignition is ON. The test will fail if the ISO-COM adapter does not receive a 12V feed from the car.

Note that fuse S21 on the S2 protects the 12V feed that is provided by the black OBD connector, so if VAG-COM fails to establish comms then this is the first thing to check.


Last Updated 18th September 2002