Audi Workshop Service and Repair Manuals

The quantity adjuster is an electromagnetic swivelling positioner that is controlled by the control unit by a specific duty cycle. The eccentric shaft on the quantity adjuster moves the modulating piston on the high pressure piston and thereby regulates the quantity of fuel injected.

The modulating piston movement sender informs the control unit of the modulating piston position, thereby indicating the quantity of fuel injected.

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select the engine electronics control unit using "Address word" 01. For this purpose, the engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit .)

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 0 and 1 for "display group number 1" and confirm entry with Q key.

• ‒ Check display in display zone 4 (coolant temperature).

Do not continue with check until coolant temperature is reached.

• ‒ Switch off any electrical consumers that may be on (air conditioner, rear window heater, lights etc.).
• ‒ Check display in display zone 3 (voltage supplied from modulating piston movement).

If specified value is not attained:

• ‒ Replace the injection pump.

Electrical check of modulating piston movement sender (G149) and quantity adjuster (N146)

• ‒ Switch ignition off.
• ‒ Detach the connector for the sensor => overview of fitting locations, Page 23-4.
• ‒ Connect hand-held multimeter (resistance test range) between the following contacts on the injection pump connector:

→ Wiring measurement on vehicles with 8-pin connector.

→ Wiring measurement on vehicles with 10-pin connector.

If the specified values are not obtained:

• ‒ Replace the injection pump.

Checking power supply and wiring connections

• ‒ Switch ignition off.
• ‒ Detach the connector for the sensor=> overview of fitting locations, Page 23-4.
• ‒ Switch the ignition on.
• ‒ Connect hand-held multimeter (voltage test range) between the following contacts on the wiring harness connector:

→ Voltage measurement on vehicles with 8-pin connector.

→ Voltage measurement on vehicles with 10-pin connector.

If the specified values are not obtained: Check wiring connections

Checking wiring

• ‒ Connect test box V.A.G 1598/22 to wiring harness for engine control unit .

The following wiring connections are to be checked for open circuits and/or short to positive or negative.

→ Wiring measurement on vehicles with 8-pin connector.

→ Wiring measurement on vehicles with 10-pin connector.

• ‒ Rectify any open/short circuit as necessary.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder