Vacuum Control Solenoid Valve Signal Check
- Warm engine to normal operating temperature. Stop engine and connect tachometer to engine. Connect voltmeter to negative terminal of leading vacuum control solenoid valve (do not unplug connector). Place auto. trans. vehicles in "P", man. trans. vehicles in Neutral.
- Start engine and run at idle speed. Voltmeter should read 0V at idle. When transmission is shifted into any forward or reverse gears, voltmeter should read near 12V.
- Increase engine speed to 2000 RPM. Slowly decrease engine speed from 2000 RPM and watch voltmeter. Current should stop flowing to solenoid terminals when engine speed is 1000-1200 RPM.
- Stop engine and disconnect No. 1 water temperature switch connector (located behind alternator). Connect a jumper wire between terminals of water temperature connector. Start engine and set engine speed at 2000 RPM with choke knob.
- Unplug connector from No. 2 water temperature switch (located on radiator). Check that the voltmeter reads near 12V when the connector is unplugged from the switch. Disconnect jumper wire and plug in No. 1 water temperature switch connector.
- Quickly decelerate engine speed from 3000 RPM. The voltmeter should read near 0V during deceleration and at idle speed. Trailing vacuum control solenoid valve (Green dot) is tested in the same manner.
NOTE:
Before replacing vacuum control solenoid valve, check auxiliary control unit, No. 2 water temperature switch, choke switch and choke relay as described in AUXILIARY CONTROL DEVICE article. Also check throttle sensor as described in DECELERATION CONTROL SYSTEM article.