1. Checking the operation of the indicator lamp.
A) Disconnect the fuel filter switch connector. Ground the connector terminal.
b) turn on «ignition»: The indicator lamp should be on.
If not, remove and check the lamp.
2. Checking the operation of the sensor-switch for the presence of water in the filter.
A) check the absence of continuity between the switch terminals with the float lowered.
b) check for continuity between the switch terminals with the float raised.