Work sequence

WARNING: This page is about a different car, the 2006 Volkswagen Golf, 2005 Volkswagen Jetta, 2005 Volkswagen Golf, 2004 Volkswagen Jetta, and 2004 Volkswagen Golf. However, it is still accessible from the selected car via links, so may be relevant.

Switch off ignition.
Remove windshield wiper arms and cover for plenum chamber: → Electrical Equipment - Repair Group 92.
Unlock and separate connector on engine control module.

Fig 1: Identifying Special Tool V.A.G 1598/31

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Connect test box V.A.G 1598/31 to control module wiring harness.
Check wiring for open circuit between test box socket 27 and instrument cluster for open or short circuit referring to wiring diagram. Wire resistance: max. 1.5 Ω Electrical Wiring Diagrams, Troubleshooting Component Locations