Note the following regarding communication problems with VW/Audi vehicles: • When testing a VW/Audi with certain ECMs, communication problems may occur when the engine speed is above 2000 RPM. In this case, communication cannot be established. Once communication has been established, the engine maybe revved above 2000 RPM. • If testing ABS/EDS/ESP/TCS systems, problems may occur if the vehicle speed exceeds 12 MPH (19 KPH. Communication will be stopped or cannot be established. B.2 The Aftermarket Radio Problem Between 1997 and 1998, VW and Audi started using radios with self-diagnostic capabilities inmost models. The scan tool can communicate with the radio, which allows you to set various options, like whether a CD player is connected, an amplified or conventional antenna, or other installed options. B.2.1 The Problem VW brought the “K-Line”, the wire on which all of the vehicle control modules communicate with the scan tool, to a pin in the connector on which older radios used to return B+ back into the harness. So if you were to take the non-diagnostics capable radio out of a 1997 GTI and put it in a 1998 where there should be a diagnostics-capable one, it fits perfectly, but the K-Line ends up shorted to power. Many aftermarket radios have adapter harnesses that plug into the vehicle radio connector. Unfortunately, some of the aftermarket harnesses faithfully reproduce the older, non-diagnostics radios with a loop of wire between Band the pin where the K-Line is on newer models. The radio will work fine until you connect a scan tool.