Audi Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ Remote control V.A.G 1348/3A with adapter cable V.A.G 1348/3-2
• ◆ Hand vacuum pump V.A.G 1390
• ◆ Adapter set V.A.G 1594

• ‒ Run engine at idling speed for 2 or 3 minutes to build up vacuum pressure.
• ‒ Switch off ignition.
• ‒ Unplug connector from intake manifold change-over valve -N156.

• ‒ → Connect one of the contacts on the solenoid valve to engine earth using test leads and crocodile clamp from V.A.G 1594.
• ‒ Connect the second contact on the solenoid valve to positive using remote control V.A.G 1348/3A, adapter lead V.A.G 1348/3-2 and auxiliary cable.

• ‒ Operate remote control V.A.G 1348/3A for about 2 or 3 minutes. During this time the vacuum unit should remain in the "pulled-in" position.

If the vacuum unit returns to its original "rest" position, carry out the following test:

• ‒ Disconnect vacuum hoses from vacuum unit for intake manifold change-over system.
• ‒ Connect hand pump V.A.G 1390 to vacuum unit.
• ‒ Operate hand pump and check whether change-over function is working.
• ‒ Test vacuum unit for leaks. (The vacuum unit should not return to the "rest" position while a vacuum is being maintained via the hand pump.)

• ‒ If necessary, renew vacuum unit.
• ‒ If the vacuum unit does not pull, test -N156 for obstructions as follows:
• ‒ → Connect one of the contacts on -N156 to engine earth using test leads and crocodile clamp from V.A.G 1594.

• ‒ Connect the other contact on -N156 to positive using remote control V.A.G 1348/3A, adapter lead V.A.G 1348/3-2 and auxiliary cable.
• ‒ Operate remote control V.A.G 1348/3A.
• ‒ Test valve for obstructions (remove vacuum hoses and blow through).
• ‒ If necessary, renew intake manifold change-over valve.
• ‒ If no faults have been found in any of the tests so far, test the vacuum system for leaks.