Testing modulating piston movement sender and quantity adjuster — AUDI

AHF ALH ASV
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.

Read measured value block, display group 01, engine at idling speed => Page
01-73

Read measured value block 1
⇒
900 rpm
5.6 mg/stroke
1.480 V
87.3 5C
Indicated on display:

Check display in display zone 4 (coolant temperature).

Read measured value block 1
⇒
900 rpm
5.6 mg/stroke
1.480 V
87.3 5C
Specified value: at least 85 °C

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).

Read measured value block 1
⇒
900 rpm
5.6 mg/stroke
1.480 V
87.3 5C
Specified value: 1.250...1.700 V

If specified value is not attained:

Replace injection pump.

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

Switch ignition off.
Remove connector from injection pump =>Fitting locations overview, page
23-4
.

Connect multimeter for resistance measurement between the following contacts on the injection pump connector:

Injection pump connector · Specified value
1 + 2 · 4.9...7.5 ω
3 + 2 · 4.9...7.5 ω
6 + 5 · 0.4...1.1 ω

If the specified values are not obtained:

Replace injection pump.

Checking power supply and wiring connections

Switch ignition off.
Remove connector from injection pump =>Fitting locations overview, page
23-4
.
Switch the ignition on.

Connect multimeter for voltage measurement between the following contacts on the wiring harness connector:

10-pin connector on wiring harness, contact · Specified value
1 + earth · approx. 2.5 V
3 + earth · approx. 2.5 V
5 + earth · approx. battery voltage

If the specified values are not obtained:

Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit => Page
23-32
.

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

10-pin connector on wiring harness, contact · Test box V.A.G 1598/31, socket
1 · 108
2 · 106
3 · 99
5 · 1. 2
6 · 116, 121

Rectify any open/short circuit as necessary.

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