Modulating piston displacement sensor, checking

• Press --> button.
• Press buttons -0- and -6- to select "End Output" function 06.
• Press -Q- button to confirm input.
• Switch ignition off.
• Disconnect fuel temperature sensor harness connector (connection to fuel pump quantity adjuster).
Fig 1: Identifying Fuel Temperature Sensor Terminals

• Measure resistance across connector terminals 1 and 2, and terminals 2 and 3.

  Specification: 5 to 7 ohms (ohm)

If resistance is not as specified:

• Replace diesel fuel injection pump, see DIESEL INJECTION PUMP, REMOVING AND INSTALLING  .
• Display readiness code, see READINESS CODE, DISPLAYING .

If DTC memory was erased:

• Create readiness code again, see READINESS CODE, SETTING (UP TO M.Y. 1997) .

If resistance is OK:

• Connect VAG1598/18 test box to Diesel DFI ECM connector.
  Fig 2: Connecting VAG1598/18 Test Box To Diesel DFI ECM Connector

  
• Check wiring for open circuit between test box and harness connector, using wiring diagrams:
  • Terminal 1 and test box socket 29
  • Terminal 2 and test box socket 7
  • Terminal 3 and test box socket 52
  • Wire resistance: max. 1.5 ohms (ohm)
  Fig 3: Identifying Fuel Temperature Sensor Harness Connector Terminals

  
• Check wiring for short circuit between connector terminals.

  Specification: INFINITY ohm (no continuity)

If wiring is OK:

• Replace Diesel DFI ECM -J248-, see item  3 .
• Display readiness code, see READINESS CODE, DISPLAYING .

If DTC memory was erased:

• Create readiness code again, see READINESS CODE, SETTING (UP TO M.Y. 1997) .