Audi Workshop Service and Repair Manuals

Testing for leaks

When there is no electrical signal the solenoid valve remains closed.

• ‒ Disconnect hoses from solenoid valve 1 for activated charcoal filter -N80.
• ‒ Connect an auxiliary hose to one of the connections on the ACF valve.
• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 (or fault reader V.A.G 1551) and select engine electronics control unit by entering address word "01" ( .)
  When doing this the ignition must be switched on.
• ‒ Start final control diagnosis and select solenoid valve for activated charcoal filter -N80 (tank breather valve)
  .

• The valve should click...
• ...and should open and close (test by blowing into auxiliary hose).

• ‒ If the valve does not click, carry out electrical test of solenoid valve 1 for activated charcoal filter => Page 24-132.
• ‒ If valve does not open and close properly, renew solenoid valve 1 for activated charcoal filter.

Electrical test of solenoid valve 1 for activated charcoal filter -N80

• ‒ Unplug connector from ACF valve -N80.
• ‒ → Measure resistance between contacts on valve using hand-held multimeter V.A.G 1526.

• Specification: 22...30 ω

If the specification is not attained:

• ‒ Renew solenoid valve for activated charcoal filter system -N80.

If the specification is obtained:

• ‒ Test voltage supply => Page 24-133.

Testing power supply to solenoid valve

Note:

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

Test conditions

• ● Fuse for ACF valve OK

• ‒ Unplug connector on ACF valve -N80.
• ‒ → Connect diode test lamp V.A.G 1527 between engine earth and socket 1 on the connector.
• ‒ Operate starter.

The diode test lamp should light up.

If diode test lamp does not light up:

• ‒ Test continuity of wiring from socket 1 to fuel pump relay via fuse. Rectify open circuit if necessary.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ‒ If wiring is OK, test fuel pump relay
  => Page 24-34.

If the diode test lamp lights up, test activation
=> Page 24-134.

Testing activation of ACF solenoid valve

• ‒ → Connect diode test lamp V.A.G 1527 between sockets 1 (positive) and 2 of plug connector.
• ‒ Start final control diagnosis and select solenoid valve for activated charcoal filter -N80
  .

The diode test lamp should flash.

If the diode test lamp does not flash or lights up continuously:

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit. Do not connect to the engine control unit itself.
  => Page 24-10.

If the diode test lamp lights up continuously:

• ‒ Test for short to earth in the following wiring connections:

If the diode test lamp does not flash:

• ‒ Test for short to positive or open circuit in the following wiring connections:

• Resistance in wiring: max. 1.5 ω

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ‒ If necessary, rectify short circuit to earth or open circuit.
• ‒ If no short circuit or open circuit is found ....
• ‒ Fit a new engine control unit -J220
  => Page 24-13.