Throttle Position Switch: Description and Operation

The closed Throttle Position (CTP) switch detects whether or not the ISC motor plunger is contacting the throttle lever screw. If the plunger is contacting the throttle lever screw, the CTP switch sends an ON signal to the PCM. When the plunger is not in contact with the throttle lever screw, the CTP switch will send an OFF signal to the PCM.

The CTP switch is located inside of the idle speed control motor. In order to service the CTP switch the idle speed control motor must be replaced.