With Generic Scan Tool

Voltage Supply For Engine Control Module (ECM), Checking

Recommended special tools and equipment







- VAG1526A hand multimeter
- VAG1594A connector test kit
- VAG1598/31 test box

Test requirements:
- Fuses for engine electronics OK
- Ground (GND) connections at engine and transmission OK
- Battery voltage at least 12.7 V
- Generator OK
- Ignition switched off.

Test sequence
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected. Test Box, Connecting For Wiring Test
- Switch ignition on.

NOTE:
- The plus voltage supply for the Engine Control Module (ECM) travels via contact 3 (terminal 15) and contact 62 (terminal 30).
- Ground (GND) supply of the Engine Control Module (ECM) travels via terminal 1 and terminal 2.

- Connect multimeter for voltage measurement as follows:

Test box Measure to
Socket
1 B+
2 B+
62 Engine Ground (GND)

- Specified value: approx. battery voltage
- Switch ignition off.

- Connect multimeter for voltage measurement as follows:

Test box Measure to
Socket
3 Engine Ground (GND)

- Switch ignition on.
- Specified value: approx. battery voltage
- Switch ignition off.

If specified values are not obtained:
- Check wire connections for open circuit according to wiring diagram:
- Specified value: Wire resistance max 1.5 Ohms
- If necessary, repair wire connection.
- Check Motronic Engine Control Module (ECM) voltage supply relay -J271-.

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1 - Check DTC memory "Mode 3: Check DTC memory". Diagnostic Mode 3: Check DTC Memory
2 - If necessary, erase DTC memory "Mode 4: Reset/erase diagnostic data". Diagnostic Mode 4: Reset/Erase Diagnostic Data
3 - Generate readiness code. Readiness Code, Generating