Throttle Full Close Switch: Description and Operation

Fig. 7 Carburetor switch location. 4-97 engine:

The carburetor switch, Fig. 7, is located on the end of the idle stop and it signals the computer when the engine is at idle. Whenever the curb idle screw touches the carburetor switch, there will be no additional advance from the vacuum transducer or changing of the carburetor air fuel ratio.