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 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 .