Vacuum Switching Valve (VSV)

Fig. 28 Testing VSV With Current Applied:

1. Disconnect wire connections and vacuum hoses from the VSV. Remove VSV from the engine.
2. Connect service wires from the VSV terminals to the battery. Fig. 28
3. Blow air into either pipe and check that air passes freely, (valve open).
4. Disconnect service wires from battery and blow air into either pipe.
5. Air should NOT pass, (valve closed).
6. If a problem is found, replace vacuum switching valve.

Fig. 30 Testing VSV For Short Circuit:

Fig. 31 Testing VSV For Open Circuit:

7. Using an ohmmeter, check the resistance between the terminals and the VSV housing. Fig. 30
8. If there is any continuity, replace the VSV.
9. Measure the resistance between the terminals of the VSV. Fig. 31
10. The resistance should be 38 - 44 Ohms at 68°F ambient temperature.
11. If resistance is not within specifications, replace VSV.
12. Reinstall VSV on the engine. Reconnect vacuum hoses and electrical connections.