1986 Pickup (Z24 engine)
- Disconnect vacuum hose from vacuum switch for spark plug switching control and connect a vacuum pump. On Federal models, except for Cab and Chassis model, connect ohmmeter leads between terminal B and body ground. With more than 3.15 in. Hg of vacuum applied, resistance should be zero. With less than 3.15 in. Hg of vacuum applied, resistance should be infinite. If test is not okay, check harness, ignition control unit and vacuum switch.
- For models others than ones mentioned in step 1), connect voltmeter between terminal B and body ground. With ignition on, pointer should deflect.