Vacuum Switch: Testing and Inspection

To test the Vacuum Switch, located on the engine, proceed as follows.

1. Remove the vacuum line from the Vacuum Switch, and connect a hand vacuum pump with a gauge.

ECU Pin Connectors:

2. Locate pin A-13 on the ECU connector and test for continuity to ground. There should be continuity.
3. Pump to more than 21.6 in.Hg, there should be NO continuity.
4. Slowly release vacuum to less than 17.8 in.Hg, there should be continuity.
5. If the Vacuum Switch fails any of these tests, disconnect the Vacuum Switch at its connector and repeat steps 2-4 checking for continuity at the switch's connector. This will determine whether the switch or the wiring harness is at fault.