Testing intake manifold change-over valve -N156 — AUDI

ARG AVV
Fitting location => Page
24-5
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Testing intake manifold change-over valve -N156

Run engine at idling speed for 2 or 3 minutes to build up vacuum.
Switch engine off.
Switch ignition on.

Final control diagnosis
⇒
Intake manifold press. change valve -N156
Perform final control diagnosis and activate intake manifold change-over valve => Page
01-42
.

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

If the valve does not click, switch off the ignition.

Unplug connector from intake manifold change-over valve -N156.
Measure resistance between contacts of solenoid valve using V.A.G 1526.

Specification: 25...35 ω

If the reading does not match the specification, renew intake manifold change-over valve -N156.

If the reading matches the specification, test voltage supply
=> Page
24-125
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Testing voltage supply to intake manifold change-over valve

-N156

Connect diode test lamp V.A.G 1527 between engine earth and socket 1 on connector using test leads from auxiliary test set V.A.G 1594.
Operate the starter briefly.

The diode test lamp should light up.

If the diode test lamp does not light up:
Test fuse for intake manifold change-over valve.

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

If the fuse is OK:

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

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

If the voltage supply is OK, test activation. => Page
24-126

Testing activation of intake manifold change-over valve

Connect diode test lamp V.A.G 1527 between sockets 1 (positive) and 2 on connector for intake manifold change-over valve using test leads from auxiliary cable set V.A.G 1594.

Final control diagnosis
⇒
Intake manifold press. change valve -N156
Perform final control diagnosis and activate intake manifold change-over valve=> Page
01-42
.

If the diode test lamp does not flash or lights up continuously, test the wiring.

Testing wiring

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
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Test the following wiring connections for open circuits and short to positive or earth.

Connector for intake manifold change-over / Socket · Test box V.A.G 1598/31 Socket
2 · 104

Resistance in wiring: max. 1.5 ω

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

If the wiring is OK, fit a new engine control unit
=>Page
24-13
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Test operation of intake manifold change-over valve -N156 again
=>Page
24-120
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