With Manufacturer's Scan Tool
Modulating Piston Displacement Sensor and Quantity Adjuster, Checking
The quantity adjuster is an electro-magnetic swivelling positioner which is controlled by the ECM via a directed duty cycle (on-off ratio). The eccentric shaft on the quantity adjuster moves the modulating piston on the high pressure piston thereby regulating the quantity of fuel injected.
The modulating piston displacement sensor -G419- informs the ECM of the position of Quantity Adjuster -N146- there determines the amount injected.
NOTE: Only gold-plated contacts must be used when repairing terminals in the connector to injection pump quantity adjuster.
Special tools and equipment
- VAG 1551/1552 Scan tool with adapter cable VAG 1551/3
- Test box VAG 1598/22
- Digital multimeter US1119 (Fluke 83 or equivalent)
- Adapter set VAG 1594
- Wiring diagram
Test conditions
- Coolant temperature must be at least 85°C See display group 01, display field 4.
Test sequence
- Connect VAG 1551/1552 (Connecting scan tool and selecting engine electronics control module). Testing and Inspection
- Run engine at idle speed and press buttons -0- and -1- to select "Engine electronics" address word 01.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read measured value block" function 08 and confirm entry with -Q- button.
Indicated on display
Read measured value block HELP
Input display group number XXX
- Press buttons -0-, -0- and -1- to select "Display group number 1" and confirm entry with -Q- button.
Indicated on display
Read measured value block 1 ->
840 rpm 6.5 mg/H 1.480 V 87.3 °C
- Check coolant temperature in display field 4
- Specification: at least 85 °C
Continue with check only when coolant temperature is attained.
Read measured value block 1 ->
840 rpm 6.5 mg/H 1.480V 87.3 °C
- Check voltage supply from modulating piston displacement sensor in display field 3.
- 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 and quantity adjuster as described in following steps:
Checking Modulating Piston Displacement Sensor -G149-.
- Disconnect 10-pin connector from modulating piston displacement sensor (connector to injection pump quantity adjuster) (arrow).
- Measure resistance between connector terminals 1 + 2 and 2 + 3.
- Specification: 4.9 to 7.5 ohms
If the specification is not obtained:
- Replace injection pump. Procedures
- Check DTC memory and, if necessary, repair any malfunctions and then erase. Testing and Inspection
- Read readiness code. Testing and Inspection
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. Testing and Inspection
If the specification is obtained:
- Remove wiper arms and plenum cover.
- Connect test box VAG 1598/22 to control module wiring harness.
- Check wiring between test box and connector for open circuit according to wiring diagram.
Terminal 1 + socket 56
Terminal 2 + socket 57
Terminal 3 + socket 64
- Wire resistance: max. 1.5 ohms
- Check wires for short to one another, to vehicle Ground and to battery positive (B+).
- Specification: Infinity ohms
If wiring and the resistance measurement values are OK:
- Replace engine control module. Service and Repair
Checking Quantity Adjuster -N146-
- Disconnect 10-pin connector from quantity adjuster connector to injection pump (arrow).
- Measure resistance between connector terminals 5 + 6.
- Specification: 0.5 to 2.5 ohms
If the specification is not obtained:
- Replace injection pump. Procedures
- Check DTC memory and, if necessary, repair any malfunctions and then erase. Testing and Inspection
- Read readiness code. Testing and Inspection
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. Testing and Inspection
If the specification is obtained:
- Remove wiper arms and plenum cover.
- Connect test box VAG 1598/22 to control module wiring harness.
- Check wiring between test box and connector for open circuit according to current flow diagram.
Terminal 5 + socket 2
Terminal 5 + socket 28
Terminal 6 + socket 59
Terminal 6 + socket 66
Terminal 6 + socket 88
- Wire resistance: max. 1.5 ohms
- Check wires for short to one another, to vehicle Ground and to battery positive (B+).
- Specification: Infinity ohms
If wiring and the resistance measurement values are OK:
- Replace engine control module. Service and Repair