Thermo Time Switch

Fig. 9 Thermo Time Switch:

When the engine coolant is below 113°F (45°C), the thermo time switch, Fig. 9, 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 time switch heats an internal element which 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.
The thermo-time switch is connected in series with a thermostatic switch that opens at 113°F (45°C). Therefore, no path to ground is available for the cold start valve or terminal TK of the time relay unless the engine coolant temperature is below 113°F (45°C).