Test sequence

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 VAG 1598/31 .
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:

SOCKETS 1, 2 & 62 VOLTAGE REFERENCE (ECM POWER SUPPLY)

Connect multimeter as follows to measure voltage:

SOCKET 3 VOLTAGE REFERENCE (ECM POWER SUPPLY)

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.
See appropriate System Wiring Diagram article.

Connect multimeter as follows to measure voltage:

SOCKET 121 VOLTAGE REFERENCE (ECM POWER SUPPLY)

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 15 minutes.

Switch ignition on.
- Specified value: approx. battery voltage
If specified value is not attained:
Check wiring connections.
See appropriate System Wiring Diagram article.
Check Motronic Engine Control Module (ECM) power supply relay -J271-. See MOTRONIC ENGINE CONTROL MODULE (ECM) POWER SUPPLY RELAY -J271-, CHECKING .