Test sequence
WARNING: This page is about a different car, the 2004 Audi A6, 2003 Audi A6, and 2002 Audi A6. However, it is still accessible from the selected car via links, so may be relevant.
- Connect test box VAG1598/31 to wiring harness for engine control module; do not connect engine control module. See WIRING AND COMPONENT CHECK WITH TEST BOX VAG1598/31 .
- Switch ignition on.NOTE:
- The positive voltage supply to the engine control module is provided via terminal 3 (terminal 15) and terminal 62 (terminal 30).
- The ground connection to the engine control module is provided via terminal 1 and terminal 2.
- Connect multimeter as follows to measure voltage:CONTROL MODULE POWER SUPPLY CIRCUIT TEST - 1 OF 3
Test box VAG1598/31 Socket Measure to 1 Battery positive 2 Battery positive 62 Engine ground - Specified value: approx. battery voltage
- Connect multimeter as follows to measure voltage:CONTROL MODULE POWER SUPPLY CIRCUIT TEST - 2 OF 3
Test box VAG1598/31 Socket Measure to 3 Engine ground - Switch ignition on.
- Specified value: approx. battery voltage
If the specified values are not obtained:
- Check wiring connections.
- Connect multimeter as follows to measure voltage:CONTROL MODULE POWER SUPPLY CIRCUIT TEST - 3 OF 3
Test box VAG1598/31 Socket Measure to 121 (1) Engine ground (1) The Motronic Engine Control Module (ECM) power supply relay -J271- carries voltage on terminal 121 of engine control modules after switching off the ignition for up to 15minutes. - Switch ignition on.
- Specified value: approx. battery voltage
If specified value is not obtained:
- Check wiring connections.
- Check Motronic ECM power supply relay -J271-. See MOTRONIC ENGINE CONTROL MODULE (ECM) POWER SUPPLY RELAY -J271-, CHECKING .