To check the throttle valve switch, begin by installing an ohmmeter to terminals I and P and check the resistance with the throttle closed. It should be O ohms. Check the mid-throttle and wide-open throttle positions. If readings are incorrect, replace the switch by removing the two screws and separating it from the throttle body, and install the new switch. Connect an ohmmeter to terminals I and P, rotating the switch until it reads O ohms, then tighten the screws.