Checking ACF solenoid 1 -N80: Audi 2.8 (AAH)

Special tools,
testers and equipment required

V.A.G 1526 A
V.A.G 1527 B
V.A.G 1594 A
VAS 5051 with VAS 5051/1

or

V.A.G 1551 with V.A.G 1551/3 A

Fitting location => Fitting locations overview, Page
24-6

Note:

Checking operation=> Read measured value bloc display group 009, Page
01-129
.

Checking for leaks

ACF solenoid valve -N80 remains closed when it is not receiving any current.

Disconnect hoses from ACF valve but leave the electrical connector plugged in.
Start final control diagnosis => Page
01-75
and actuate ACF valve.
While final control diagnosis is running, blow into solenoid valve to check whether it opens properly. If necessary, fit a new solenoid valve.

Checking internal resistance

Unplug connector on ACF valve.
Connect multimeter to valve to measure resistance
Specification: 20 ... 28 ω

If the specification is not obtained:

Fit a new ACF valve.

Checking power supply

Note:

The ACF valve receives its power supply via the fuel pump relay.

Unplug connector on ACF valve.

Connect voltage tester V.A.G 1527 B as follows:

Connector / Contact · Measure against
1 · Engine earth

Start final control diagnosis => Page
01-75
and actuate fuel pump relay -J17.
The LED should light up.

If the LED does not light up:

Carry out the following tests (marked with dots):

Check fuse S229 (in fuse holder, position 29).

Check for open circuit between contact 1 on connector and fuse in fuse holder .

=> "Current Flow Diagrams, Electrical Fault Finding and Fitting Locations" binder

Check fuel pump relay => Page
24-43

Checking actuation

Connect voltage tester V.A.G 1527 B between contacts 1 and 2 using auxiliary cables from V.A.G 1594 A.
Start final control diagnosis =>Page
01-75
and actuate ACF solenoid -N80.
The LED should flash.

If the LED lamp does not flash or if it lights up continuously:

With the ignition switched off, use adapter V.A.G 1598/12 to connect test box V.A.G 1598 A to connector D only of engine control unit (control unit remains disconnected) => Page
24-17
.

Check for open circuit and short to positive or earth in the following wiring connections:

Connector / Contact · Test box V.A.G 1598 A / Socket
2 · 12

Rectify short circuit or open circuit if necessary.

=> "Current Flow Diagrams, Electrical Fault Finding and Fitting Locations" binder

If the wiring is OK, fit a new engine control unit => Page
24-20
.