Frequency Valve: Testing and Inspection

Fig. 34 Frequency Valve Test (CIS):

1. Remove fuel pump relay and connect a jumper wire across sockets 13 and 14.
2. If equipped, disconnect air flow sensor plate position indicator plug at air flow sensor.
3. Turn ignition on.
4. The frequency valve should operate, making a buzzing noise.
5. If no buzzing is heard, check the wiring.
a. Disconnect the plug on the frequency valve.
b. Connect a voltmeter across the terminals. Battery voltage should be available while fuel pump is energized, Fig. 34.
c. If no voltage is present, check ground circuit, power circuit, and check wiring for breaks.
6. If voltage is present, and wiring os OK, replace frequency valve.