Turbo

Fig. 29 Thermostatic Switches:

The thermostatic switch, Fig. 29, is closed at temperatures below 77°F (25°C). If the temperature has been higher than this, the switch will not close until the temperature has fallen to 66°F (19°C).
The switch is connected in parallel with terminal 12 in the ECU. At temperatures below 77°F (25°C), terminal 12 in the ECU is grounded and a fixed pulse ratio of 60° is selected. At temperatures above 77°F (25°C), the thermostatic switch is open and the preset pulse ratio is not selected.