Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ V.A.G 1390
• ◆ V.A.G 1526 A
• ◆ V.A.G 1527 B
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31

Checking function

• ‒ Start engine and run at idling speed.
• ‒ Switch off ignition.
• ‒ Observe positioning lever on intake manifold flap (2nd person required).
• ‒ After switching off the ignition, the intake manifold flap should close and open again after approx. 3 seconds.

If change-over does not occur, the following checks must be carried out.

• ‒ Check intake manifold flap change-over mechanics for freedom of movement. To do this operate rods by hand.
• ‒ Check function of vacuum positioning element with hand vacuum pump V.A.G 1390.
• ‒ Check vacuum pipes for correct connection.

If no fault is found in the mechanical components:

• ‒ Unclip protecting covers.
• ‒ → Unscrew bolts -arrows- and remove air cleaner cover.
• ‒ Unplug connector on intake manifold flap change-over valve -N239.

Testing internal resistance

• ‒ → Connect multimeter to valve (resistance measurement range)
• ‒ Specification: 25 ... 45 ω

If the specification is not obtained:

• ‒ Renew intake manifold flap change-over valve.

Checking voltage supply

Test requirement:

• ● Fuse for intake manifold flap change-over valve OK

• ‒ → Connect multimeter (voltage measurement range) as follows:

• ‒ Switch on ignition.
• ‒ Specification: approx. battery voltage

If the specification is not obtained:

• ‒ Test wiring for open circuits and rectify if necessary.

Checking activation

• ‒ → Connect voltage tester V.A.G 1527 B between contacts 1 and 2
• ‒ Start final control diagnosis and select intake manifold flap change-over valve -N239 =>Page 01-55.
• ‒ The LED should flash slowly.

Note:

The LEDs on voltage testers with a low current draw continue to glow faintly between impulses from the engine control unit (rather than going out completely) and become much brighter when receiving an impulse.

• ‒ Finish off final control diagnosis.
• ‒ Select diagnosis function "06 - End output" Page 01-11.
• ‒ Switch off ignition.

If the LED does not react as described:

• ‒ 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 23-37.

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

• ‒ Rectify any open/short circuit as necessary.

If no fault is found:

• ‒ Fit a new engine control unit => Page 23-40.