Component Tests and General Diagnostics

The fuel economy warning light should go on when the ignition is turned on. If it does not light, disconnect the wire from the fuel economy vacuum switch connector and ground the wire to the frame or cylinder block. If the warning light still does not go on, check for burned out indicating bulb or an open in the harness between the vacuum switch and instrument panel. If the warning light goes on, circuit is functioning and the vacuum switch should be checked for proper ground. Remove and clean the mounting bracket screws and the mounting surfaces.
If system still does not operate, perform the following: With the electrical connector and vacuum tube disconnected from the switch, connect a self-powered test light to the switch electrical connector and to the vacuum gauge mounting bracket. Attach a vacuum pump to the gauge. If the following conditions are not met, the switch has to be replaced:
1. With vacuum applied, test light should be off.
2. With no vacuum to the vacuum switch, test light should be on.
If the warning light remains lit when it normally should be out, check vacuum hose to vacuum switch for damage or plugged condition.