Vacuum System, Checking For Leaks

Vacuum System, Checking For Leaks







Special tools and equipment
- VAG1348/3-2
- VAG1348/3A
- VAG1390
- VAG1594 A

Test sequence
- Run engine at idling speed for 2 or 3 minutes to build up vacuum pressure.
- Switch ignition off.







- Remove front engine cover (arrows).







- Disconnect connectors to intake manifold change-over valve -N156- -1-.







- Connect one terminal on solenoid valve to engine Ground using test leads and alligator clamp from VAG1594 A.
- Connect second terminal on intake manifold change-over valve -N156- to positive using remote control VAG1348/3A, adapter lead VAG1348/3-2 and auxiliary cable.
- Operate remote control VAG1348/3A approx. 2 to 3 minutes; throughout this period, vacuum module should remain energized.

If the vacuum module retardations to its original "rest" position, perform the following test:
- Disconnect vacuum hoses from vacuum module for intake manifold change-over system.
- Connect hand vacuum pump VAG1390 to vacuum module.
- Operate hand pump and check whether change-over function is working.
- Check vacuum module for leaks. (Vacuum module should not return to rest position until hand pump is vented to atmosphere.)
- Replace vacuum module, if necessary.
- If vacuum module is not energized, check intake manifold change-over valve -N156- as follows for blockage:







- Connect one terminal of intake manifold change-over valve -N156- to engine Ground using test leads and alligator clamp from VAG1594 A.
- Connect second terminal on intake manifold change-over valve -N156- to positive using remote control VAG1348/3A, adapter lead VAG1348/3-2 and auxiliary cable.
- Operate remote control VAG1348/3A.
- Check valve for obstructions (disconnect vacuum hoses and blow through).
- Replace intake manifold change-over valve, if necessary.
- If no DTCs have been found in any test, check vacuum system for leaks.