Test sequence

• Connect V.A.G 1551/1552, see VAG 1551 SCAN TOOL, CONNECTING .
• Run engine at idle speed and press buttons -0- and -1- to select "Engine electronics" address word 01.

  Indicated on display

  Fig 1: Scan Tool Display - Modulating Piston Displacement Sensor And Quantity Adjuster Test Sequence (1 Of 4)

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Press buttons -0- and -8- to select "Read measured value block" function 08 and confirm entry with -Q- button.

  Indicated on display

  Fig 2: Scan Tool Display - Modulating Piston Displacement Sensor And Quantity Adjuster Test Sequence (2 Of 4)

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Press buttons -0-, -0- and -1- to select "Display group number 1" and confirm entry with -Q- button.

  Indicated on display

  Fig 3: Scan Tool Display - Modulating Piston Displacement Sensor And Quantity Adjuster Test Sequence (3 Of 4)

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Check coolant temperature in display field 4
  • Specification: at least 85 °C

  Continue with check only when coolant temperature is attained.

• Check voltage supply from modulating piston displacement sensor in display field 3.
  Fig 4: Scan Tool Display - Modulating Piston Displacement Sensor And Quantity Adjuster Test Sequence (4 Of 4)

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
  • Specification: 1.450 to 2.000 Volts
• Press the --> button.
• Press buttons -0- and -6- to select "End output" function 06 and confirm entry with -Q- button.
• Switch ignition off.

If specification is not obtained, check modulating piston displacement sensor -G419- and quantity adjuster as described in following steps:

Checking Modulating Piston Displacement Sensor -G149-  .

• Disconnect 10-pin connector from modulating piston displacement sensor -G419- (connector to injection pump quantity adjuster) (arrow).
Fig 5: Disconnecting 10-Pin Connector From Modulating Piston Displacement Sensor
Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Measure resistance between connector terminals 1 + 2 and 2 + 3.
  • Specification: 4.9 to 7.5

Fig 6: Identifying 10-Pin Connector Terminals

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

If the specification is not obtained:

• Replace injection pump, see INJECTION PUMP, REMOVING AND INSTALLING .
• Check DTC memory and, if necessary, repair any malfunctions and then erase: see DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING .
• Read readiness code, see READINESS CODE, DISPLAYING .

  If the DTC memory has been erased or the engine control module was disconnected from permanent battery positive (B+), the readiness code must be generated again. See READINESS CODE, SETTING .

If the specification is obtained:

• Remove wiper arms and plenum cover.

  See Plenum Cover Emoval & Installation

• Connect test box VAG 1598/22 (through my 1999) or VAG 1598/31 (from my 2000) to control module wiring harness.
  Fig 7: Connecting Test Box VAG 1598/22 Or VAG 1598/31 To Control Module Wiring Harness

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Check wiring between test box and connector for open circuit according to wiring diagram.
  Fig 8: Identifying 10-Pin Harness Connector Terminals

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
  10-PIN HARNESS CONNECTOR TERMINAL SPECIFICATIONS (MODULATING PISTON DISPLACEMENT SENSOR)
  
  

  	Test box socket no.
  Terminal	Through MY 1999	From MY 2000
  1	56	108
  2	57	106
  3	64	99

  • Wire resistance: max. 1.5 Ω
• Check wires for short to one another, to vehicle Ground and to battery positive (B+).
  • Specification: INFINITY Ω

If wiring and the resistance measurement values are OK:

• Replace engine control module, see DIESEL DIRECT FUEL INJECTION (DFI) ENGINE CONTROL MODULE (ECM) -J248-, REPLACING .

Checking Quantity Adjuster -N146- 

• Disconnect 10-pin connector from quantity adjuster (connector to injection pump) (arrow).
  Fig 9: Disconnecting 10-Pin Connector From Quantity Adjuster (Connector To Injection Pump)

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Measure resistance between connector terminals 5 + 6.
  • Specification: 0.5 to 2.5 Ω

Fig 10: Identifying 10-Pin Connector Terminals

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

If the specification is not obtained:

• Replace injection pump, see INJECTION PUMP, REMOVING AND INSTALLING .
• Check DTC memory and, if necessary, repair any malfunctions and then erase. See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING .
• Read readiness code, see READINESS CODE, DISPLAYING .

  If the DTC memory has been erased or the engine control module was disconnected from permanent battery positive (B+), the readiness code must be generated again. See READINESS CODE, SETTING .

If the specification is obtained:

• Remove wiper arms and plenum cover.

  See Plenum Cover Emoval & Installation

• Connect test box VAG 1598/22 (through my 1999) or VAG 1598/31 (from my 2000) to control module wiring harness.
  Fig 11: Connecting Test Box VAG 1598/22 Or VAG 1598/31 To Control Module Wiring Harness

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Check wiring between test box and connector for open circuit according to current flow diagram.
  Fig 12: Identifying 10-Pin Harness Connector Terminals

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
  10-PIN HARNESS CONNECTOR TERMINAL SPECIFICATIONS (QUANTITY ADJUSTER)
  
  

  	Test box socket no.
  Terminal	Through MY 1999	From MY 2000
  5	2	1
  5	28	2
  6	80	116
  6	80	121
  6	80	-

  • Wire resistance: max. 1.5 Ω
• Check wires for short to one another, to vehicle Ground and to battery positive (B+).
  • Specification: INFINITY Ω

If wiring and the resistance measurement values are OK:

• Replace engine control module, see DIESEL DIRECT FUEL INJECTION (DFI) ENGINE CONTROL MODULE (ECM) -J248-, REPLACING .