Vacuum Pull-Off Automatic Choke: Operation
Solenoid vacuum valve, mounted on firewall, controls vacuum acting upon vacuum pull-off diaphragm. Solenoid valve is activated by electrical current from ignition switch. Flow of current to solenoid valve is controlled by low temperature and transmission switches. Temperature switch is closed at temperatures under and open over 60°F. Transmission switch is open when in high gear. Therefore, when temperature is below 60°F, normal automatic choke operation will result even if transmission is in high gear. When temperature exceeds 60°F and transmission is in high gear normal choke operation will be overridden and choke will be in wide open position. See Electric Assist Choke in this section for further detail operation.