Audi Workshop Service and Repair Manuals

Electrical test of intake manifold change-over valve

-N156

Fitting location .

• ‒ Unplug connector on intake manifold change-over valve.
• ‒ → Measure resistance at intake manifold change-over valve.
• ‒ Specification: 25 ... 35 ohm

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

Testing power supply to intake manifold change-over valve

-N156

• ‒ → Unplug connector for intake manifold change-over valve.

• ‒ Connect diode test lamp V.A.G 1527 between engine earth and contact 1 (positive) on connector using cables from adapter set V.A.G 1594.
• ‒ Operate starter briefly (the engine can be allowed to start).

• Specification: The diode test lamp should light up.

If the diode test lamp does not light up, carry out the following tests:

• ‒ Test fuse for -N156.
• ‒ Test for open circuit in wiring between fuse and contact 1 on connector for intake manifold change-over valve using current flow diagram.

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

• Specification: max. 1 ohm

• ‒ Test fuel pump relay and activation
  .

Testing activation of intake manifold change-over valve

• ‒ → Connect diode test lamp V.A.G 1527 between contacts 1 (positive) and 2 (activation signal from engine control unit) on connector for intake manifold change-over valve using cables from adapter set V.A.G 1594.
• ‒ Start final control diagnosis. The diode test lamp should flash when the intake manifold change-over valve is being activated.
• ‒ If the diode test lamp does not flash or if it lights up continuously, connect test box V.A.G 1598/22 to wiring harness for engine control unit
  .
• ‒ If the diode test lamp lights up continuously, test for short to earth in wiring between contact 2 on connector for intake manifold change-over valve and socket 64 on test box.

• ‒ If the diode test lamp does not flash, test for open circuit or short to positive in wiring between contact 2 on connector for intake manifold change-over valve and socket 64 on test box.

• Specification: max. 1 ohm

• ‒ → If necessary, rectify open circuit or short to earth.
• ‒ If there is no open circuit and no short circuit, fit a new engine control unit
  => Page 24-15.