Evaporative Emissions System: Testing and Inspection

Fig. 61 Speed Sensor Test:

1. Raise and support vehicle so one rear wheel is off ground.
2. Release parking brake, place shift lever in neutral, and disconnect wiring connector from computer.
3. Connect ohmmeter, Fig. 61.
4. Turn rear wheel slowly and ensure ohmmeter needle deflects consistently.
5. If ohmmeter needle does not deflect, check for proper connection of speed sensor terminals at rear of speedometer.
6. If connection is satisfactory, replace speedometer assembly.
7. Reconnect wiring connector to computer.

Fig. 56 Vacuum Gauge Hookup:

SPEED SENSOR TO VACUUM SWITCHING VALVE CIRCUIT

1. Using a 3-way connector, connect vacuum gauge to hose between vacuum switching valve and charcoal canister, Fig. 56.
2. Position gauge so it is readable from driver's seat, and run vehicle until it reaches normal operating temperature.
3. Road test vehicle and ensure vacuum gauge indicates zero vacuum below 7 mph, and intake manifold vacuum at speeds above 16 mph.
4. If vacuum is not as described in step 3, test speed sensor and vacuum switching valve.