Throttle Positioner System

1975-82
1. Disconnect vacuum hose between throttle positioner diaphragm and vacuum switching valve.

2. On 1975 models, connect a vacuum gauge to vacuum switching valve and place gauge where it can be observed while driving the vehicle.

3. On 1976-82 models, connect a vacuum gauge between throttle positioner and vacuum switching valve, then place gauge where it can be observed while driving the vehicle.

4. Road test vehicle while observing the vacuum gauge readings at various vehicle speed. When gauge indicates vacuum, the system is off. When gauge indicates near zero vacuum, the system is on.

5. If system is not operating properly, refer to "System Testing" diagnosis under "Evaporative Emission Control System" to check system.