Audi Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ Hand multimeter V.A.G 1526 or V.A.G 1526 A
• ◆ Diode test lamp V.A.G 1527
• ◆ Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/3
• ◆ Adapter set V.A.G 1594

Testing for leaks

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

• ‒ Disconnect hoses from solenoid valve for activated charcoal filter
  -N80.
• ‒ Connect plug to solenoid valve.
• ‒ Start final control diagnosis and select solenoid valve for activated charcoal filter -N80
  .
• ‒ While final control diagnosis is running, blow into the solenoid valve to check whether it opens and closes properly. If necessary, fit a new solenoid valve.

Electrical test of -N80 (ACF valve)

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

Specification: 22...30 ω.

• ‒ If the value is not as specified, fit a new ACF valve.

Testing power supply to ACF 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.
• ‒ → Connect diode test lamp V.A.G 1527 between engine earth and contact 1 on the connector.

• ‒ Operate starter.

• Specification: The diode test lamp should light up.

• ‒ If diode test lamp does not light up, test for open circuit between contact 1 and fuse. Rectify open circuit if necessary.

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

• ‒ If wiring is OK, test fuel pump relay
  .

Testing ACF valve activation

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

• Specification: The diode test lamp should flash.

• ‒ If the diode test lamp does not flash or lights up continuously, connect test box V.A.G 1598/22 to wiring harness for engine control unit => Page 24-8.

• ‒ → If the diode test lamp lights up continuously, test for short circuit to earth in wiring between contact 2 on ACF valve connector and socket 15 on test box.
• ‒ If the diode test lamp does not flash, test for open circuits and short circuits to positive in the wiring between contact 2 on ACF valve connector and socket 15 on test box.

Specification: max. 1 ω.

• ‒ 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 => Page 24-10.