Test step 1

WARNING: This page is about a different car, the 2004 Volkswagen R32. However, it is still accessible from the selected car via links, so may be relevant.

This checks the voltage supply of All-Wheel Drive Control Module -J492-.

Set measuring range to 20 V.
Switch on ignition.

Fig 1: 8-Pin Connector & Terminals

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Measure between terminal - 1 - and terminal - 2 - (Ground) on disconnected connector.

Specified value: Battery voltage

If specified value not obtained:

Repair wiring routing according to wiring diagram Electrical Wiring Diagrams, Troubleshooting Component Locations.
Switch ignition off.