With Generic Scan Tool

Voltage supply for Engine Control Module (ECM), checking

Recommended special tools and equipment

- VAG 1526 multimeter or VAG 1715 multimeter
- VAG 1594 connector test kit
- Wiring diagram

Test requirements







- The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK.
- Fuel Pump (FP) Relay -J17- must be OK, check.
- Generator (GEN) must be OK, checking.
- Battery voltage must be at least 11.5 volts.
- All electrical consumers such as, for example, lights and rear window defroster must be switched off.
- Parking brake must be engaged or else daylight driving lights will be switched on.
- If vehicle is equipped with an A/C system, it must be switched off.
- Ground (GND) connections between engine and chassis must be OK.

Test sequence

- Connect test box to control module wiring harness, connect test box for wiring test. Test Box, Connecting For Wiring Test

Checking voltage supply terminal 30

Vehicles with engine code AEG

- Measure voltage supply between sockets 2 + 3 of test box. Specified value: at least 11.5 V

Vehicles with engine code AVH, AZG, BDC

- Measure voltage supply between sockets 1 + 62 and 2 + 62 of test box. Specified value: at least 11.5 V

Continuation for all vehicles

If specified value is not obtained:
- Check wire connections to relay carrier and Ground (GND) connection of Engine Control Module (ECM) according to wiring diagram.
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

Checking voltage supply terminal 15

Vehicles with engine code AEG

- Measure voltage supply between sockets 1 + 2 of test box.

Vehicles with engine code AVH, AZG, BDC

- Measure voltage supply between sockets 1 + 3 and 2 + 3 of test box.

Continuation for all vehicles

- Switch ignition on. Specified value: at least 11.5 V

If specified value is not obtained:
- Check wire connections to relay carrier and Ground (GND) connection of Engine Control Module (ECM) according to wiring diagram.
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes