Checking intake manifold flap switching action: Audi 1.9 TDI (AJM, AVF, AWX)

AVF AWX
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 operation

Start engine and let it idle.
Switch off ignition.
Observe control lever at intake manifold flap (2nd mechanic required).
Intake manifold flap must close after switching off ignition and open again after approx. 3 seconds

Perform the following checks if there is no switching action.

Check freedom of movement of switching mechanism of intake manifold flap by moving linkage manually.
Check operation of vacuum actuator with vacuum hand pump V.A.G 1390.
Check proper connection of vacuum pipes.

If no fault is found in mechanical components:

Unclip caps.
Screw out bolts -arrows- and detach air cleaner cover.
Unplug connector at intake manifold flap changeover valve -N239.

Checking internal resistance

Vehicles with engine code letters AJM:

Connect multimeter to valve for resistance measurement.

Vehicles with engine code letters AVF, AWX:

Connect up multimeter for resistance measurement between contacts 1 and 2.

All models:

Specification: 25 ... 45 ω

If reading does not match specification:

Replace intake manifold flap changeover valve.

If reading matches specification:

Checking power supply

Test requirement:

Intake manifold flap changeover valve fuse OK

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

Diesel direct injection system relay OK; checking => Page 23-65

Vehicles with engine code letters AJM:

Connect up multimeter for voltage measurement as follows.

Connector / Contact · Measure to
1 · Engine earth

Vehicles with engine code letters AVF, AWX:

Connect up multimeter for voltage measurement as follows.

Connector / Contact · Measure to
1 · Engine earth

All models:

Switch on ignition.
Specification: approx. battery voltage

If reading does not match specification:

Check for open circuit in wiring and repair if necessary.

If reading matches specification:

Checking actuation

Vehicles with engine code letters AJM:

Connect up voltage tester V.A.G 1527 B between contacts 1 and 2.

Vehicles with engine code letters AVF, AWX:

Connect up voltage tester V.A.G 1527 B between contacts 1 and 2.

All models:

Start final control diagnosis and actuate intake manifold flap changeover valve -N239 =>Page 01-55.
LED must flash slowly

Note:

Voltage testers with a low current input do not go out completely between actuation of engine control unit, but rather continue to glow slightly and become distinctly brighter on actuation.

Complete final control diagnosis.
Select diagnosis function "06 - End of output" in list => Page 01-11.
Switch off ignition.

If LED does not react as described:

Connect test box V.A.G 1598/31 to engine control unit wiring harness. Actual engine control unit is not to be connected=>Page 23-50.

Vehicles with engine code letters AJM:

Check for open circuit and short to earth/positive in the following wiring.

Connector / Contact · Test box V.A.G 1598/31 / Socket
2 · 81

Vehicles with engine code letters AVF, AWX:

Check for open circuit and short to earth/positive in the following wiring.

Connector / Contact · Test box V.A.G 1598/31 / Socket
2 · 81

All models:

If necessary, eliminate open circuit in wiring/short circuit.

If no fault is found:

Replace engine control unit => Page 23-52.