Vacuum System, Checking For Proper Seal

Special Tools and Equipment







- VAG1348/3-2
- VAG1348/3A
- VAG1390
- VAG1594A

- Let vehicle run at idle for 2 to 3 minutes (vacuum build-up).
- Switch ignition off.
- Disconnect connector from Intake Manifold Change-Over Valve -N156-.







- Connect one terminal of solenoid valve to engine Ground (GND) using an adapter cable and an alligator clip from VAG1594A connector test kit.
- Connect the second terminal of solenoid valve to B+ using VAG1348/3A remote control, VAG1348/3-2 adapter cable and assisting cable.
- Operate VAG1348/3A remote control for approx. 2 to 3 minutes. Vacuum diaphragm must remain activated during this time.

If the vacuum diaphragm moves back, check vacuum reservoir as follows:
- Disconnect vacuum hoses from vacuum reservoir for intake manifold change-over.
- Connect VAG1390 hand vacuum pump to vacuum reservoir.
- Operate hand vacuum pump and observe change-over procedure.
- Check vacuum reservoir for proper seal. (Vacuum reservoir must not return to rest position, as long as the hand vacuum pump is not vented.)
- Replace vacuum reservoir if necessary.

- If the vacuum diaphragm does not activate, check Intake Manifold Change-Over Valve -N156- for continuity as follows:







- Connect one terminal of Intake Manifold Change-Over Valve -N156- to engine Ground (GND) using an adapter cable and an alligator clip from VAG1594A connector test kit.
- Connect the second terminal of Intake Manifold Change-Over Valve -N156- to B+ using VAG1348/3A remote control, VAG1348/3-2 adapter cable and assisting cable.
- Operate VAG1348/3A remote control.
- Check valve for throughput (disconnect vacuum hose and blow through).
- If necessary, replace intake manifold change-over valve.
- Check vacuum system for leaks if no malfunctions were detected for all previous tests.