Electrical Signal

Fig. 3 Vacuum routing.:

These models are equipped with both leading and trailing vacuum control solenoid valves.
1. To check signal for leading vacuum control solenoid valve, proceed as follows:
a. Start and operate engine until normal operating temperature is obtained.
b. Connect a tachometer onto engine as per manufacturer's instructions.
c. Disconnect vacuum sensing tube from vacuum line.
d. Place a finger over portion of vacuum line and ensure air is not sucked into line.
e. Gradually increase engine speed and ensure air is sucked into line when engine speed reaches 1000---1200 RPM or more.
f. Increase engine speed to 4000 RPM, then quickly decrease engine speed and ensure air is not sucked into line while decelerating.
g. On automatic transmission models, operate engine at idle speed and ensure air is sucked into line when transmission shift lever is in R, D, D1 or D2 positions.
h. On all models, disconnect electrical connector from No. 1 water temperature switch and connect a jumper wire to both terminals on connector. Pull choke knob out approximately .6 inch and ensure air is not sucked into line at any engine speed.
i. Turn ignition switch to OFF position and disconnect electrical connector from No. 2 water temperature switch on radiator. Pull choke knob out approximately .6 inch and start engine. Increase engine speed and ensure air is sucked into line when engine speed reaches 1000-1200 RPM.
2. To check signal for trailing vacuum control solenoid valve, proceed as follows:
a. Start and operate engine until normal operating temperature is obtained.
b. Connect a tachometer onto engine as per manufacturer's instructions.
c. Disconnect vacuum sensing tube from vacuum line.
d. Place a finger over open portion of vacuum line and ensure air is not sucked into line.
e. Increase engine speed and ensure air is sucked into line when engine speed increases to 2900-3100 RPM.
f. Increase engine speed to 4000 RPM, then quickly decrease engine speed and ensure air is not sucked into line while decelerating.
g. On automatic transmission models, operate engine at idle and ensure air is sucked into line when transmission shift lever is in R, D, D1 or D2 positions.
h. Perform steps 1h and 1i.