Emission Control Systems: Testing and Inspection

1. Visually check fuel shut-off system and replace any broken or damaged switches.
2. Run engine until it reaches normal operating temperature and make sure choke valve is fully open.
3. Disconnect anti-dieseling solenoid valve connector. If engine does not stop, replace anti-dieseling solenoid valve assembly.
4. Raise and support vehicle so that drive wheels are off ground and block other wheels.
5. Connect circuit tester to function test connector, start engine, and shift lever to top position for manual transmission or drive position for automatic transmission.
6. Maintain speed of 50 m.p.h., then quickly close throttle valve by releasing accelerator pedal. Never exceed 55 m.p.h.
7. Check for voltage across "LY" and "B".
8. If voltage reading is zero or 12 volts at all speeds, system is malfunctioning Test vacuum switch first then test other switches.