Throttle Position Switch: Description and Operation

Throttle Body Assembly - Exploded View:

ISC Circuit:

THROTTLE SWITCH
An integral part of the Idle Speed Control (ISC) actuator is the throttle switch. The position of the throttle switch determines whether or not the ISC controls idle speed. When the throttle lever rests against the ISC plunger, the switch contacts are closed and the Powertrain Control Module (PCM) moves the ISC plunger to the programmed idle speed setting. When the throttle lever breaks contact with the ISC plunger, the switch contacts open and the PCM stops sending idle speed control commands. Engine speed is again controlled by the accelerator pedal.