Thermo Time Switch

Function

When control units were scarce, yet the vehicle featured an auxiliary injector, the injector was controlled via a thermo time switch and the current on board.

How it works

Actually, it has three connections if you count ground, too. Two connections are responsible for heating a bimetal. Via the third connection (ground) the current is switched to the cold start valve. From a certain temperature of the coolant onward the injector is anyway switched off. The lower the temperature, the longer it takes to heat the bimetal and to disconnect its contact.
Thus the injection time for the cold start valve could be up to 8 seconds.