There are 2 switches on the throttle body, one above and one below. The lower switch signals the ECU when the throttle is at idle and the upper switch signals full throttle. This information is used to calculate fuel shut-off and ignition timing during deceleration, idle stabilizer valve operation and full throttle enrichment. If there is a problem with any of these functions, check these switches first.
- Locate the switches on the throttle body and unplug the connector.
- Connect an ohmmeter to the idle switch and make sure it is closed when the throttle is against the stop. Open the throttle, position a 0.024 inch (0.60mm) feeler gauge against the stop and let the throttle close on the gauge. The switch must remain open. DO NOT adjust the throttle stop screw.
- Connect the ohmmeter to the full throttle switch. Open the throttle all the way to the stop and make sure the switch closes. The switch should open when the throttle is allowed to close 10 degrees from the stop.
- Turn the ignition switch ON and use a voltmeter to check for 5 volts at each switch connector. This signal comes directly from the ECU.