Fuel Delivery and Air Induction Thermo Time Switch Component Locations
Thermo Time Switch: Description and Operation
The cold start valve is an electrically controlled fuel injector mounted in the intake manifold. When the valve is energized additional fuel is injected into
the manifold to aid cold starting. Current flow through the cold start valve solenoid is controlled by the thermo timing switch.
When the engine and switch are both below the switch calibration temperature, the switch is closed completing the cold start valve ground circuit. During
cranking battery voltage is applied to both the cold start valve and timing switch, and the start valve injects fuel into the manifold. After 3 - 10 seconds,
voltage applied to the thermo timing switch heats the element within the switch, the element expands opening the cold start valve ground circuit and the
cold start valve is de-energized. When coolant temperature exceeds the switch calibration temperature, the switch remains open and the cold start valve
does not operate.
