Checking solenoid valves -N156 and -N261 for intake manifold changeover — AUDI

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Run engine at idling speed for 2 or 3 minutes to build up vacuum pressure.
Switch engine off.
Switch the ignition on.
Perform final control diagnosis and activate intake manifold changeover solenoid valves
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Final control diagnosis
⇒
Intake manifold changeover valve
-N156
Indicated on display:

Final control diagnosis
⇒
Intake manifold changeover valve 2
-N261
Indicated on display:

The solenoid valves should click (clicking can be heard and felt). After 1 minute the final control diagnosis is terminated.

If one of the solenoid valves does not click.
Switch ignition off.

Unplug connector from relevant intake manifold change-over solenoid valve.
Measure resistance between the solenoid valve contacts using V.A.G 1526.

Specified value: 25...35 Ohms

If the specified value is not achieved, renew the solenoid valve for intake manifold changeover.

If specification is attained, check voltage supply => Page
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Checking voltage supply of intake manifold changeover solenoid valve

Connect diode test lamp V.A.G 1527 between engine earth and socket 1 (positive) on connector using cables from adapter set V.A.G 1594.
Operate starter briefly.

The diode test lamp should illuminate.

If the diode test lamp does not illuminate.
Check fuse for intake manifold change-over solenoid valve.

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

If the fuse is OK:

Check for open circuit and short in wiring between fuel pump relay and socket 1 on connector via fuse for intake manifold change-over solenoid valve.

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

If the voltage supply is OK, check actuation => Page
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Re-insert the fuel pump relay and fuse.

Checking actuation of intake manifold changeover solenoid valve

Connect diode test lamp V.A.G 1527 between sockets 1 and 2 on connector for intake manifold changeover solenoid valve using cables from adapter set V.A.G 1594.
Perform final control diagnosis and actuate relevant solenoid valve for intake manifold changeover solenoid valve => Page
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Final control diagnosis
⇒
Intake manifold changeover valve
-N156
Indicated on display:

Final control diagnosis
⇒
Intake manifold changeover valve 2
-N261
Indicated on display:

If the diode test lamp does not flash or is continuously lit: Check the wiring.
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Checking wiring

Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit => Page
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Check the following wiring connections for open circuit and short circuit to positive or earth.

Intake manifold changeover connector 1 -N156 / socket · Test box V.A.G 1598/31 socket
2 · => Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder
Intake manifold changeover connector 2 -N261 / socket · Test box V.A.G 1598/31 socket
2 · => Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

Wire resistance: max. 1.5 Ohm

Rectify any open/short circuit as necessary.

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

If the wiring is OK replace engine control unit => Page
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Check intake manifold changeover valve again for function =>Page
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