Audi Workshop Service and Repair Manuals > A3 Mk1 > Power unit | Simos injection and ignition system (4-cylinder) | Mixture preparation system, electronic inj.,Gas | Checking intake manifold changeover function | Checking intake manifold changeover valve N156 | Checking actuation of intake manifold changeover valve

Checking actuation of intake manifold changeover valve

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

–	Start final control diagnosis and actuate the intake manifold changeover valve.

t	The LED should flash.

If the LED lamp does not flash or lights up continuously:

–	Connect test box -V.A.G 1598/31- to wiring harness for engine control unit. Do not connect engine control unit → Chapter.

–	Check for open circuit and short to positive or earth in the following wiring connections:

Connector Contact	Test box -V.A.G 1598/31- Socket
2	117

–	Rectify any open/short circuit as necessary. → Current flow diagrams, Electrical fault finding and Fitting locations

If the wiring is OK:

–	Replace engine control unit → Chapter.