Where should I look if the illuminated switch does not light?
The light is a supply indicator; if it does not light, first measure the fuse and the battery voltage, then confirm that the switch connector is seated and that the chassis connection is made to clean metal. If the light does not come on but the motor runs, the problem is only in the indicator circuit; if the light comes on but the motor does not turn, supply is present and the fault is in the contact or the mechanics.
Use the light as an independent diagnostic tool, because it tells you the state of the supply line:
- No light, no motor: Supply is cut. Measure the fuse, battery terminals, main supply cable and chassis connection in turn.
- No light, motor runs: Supply is sound, only the indicator circuit or the lamp is faulty. It does not prevent operation, but the socket contact may be starting to weaken; check it.
- Light on, no motor: There is voltage at the unit. Measure contact continuity and the voltage at the unit's supply terminals, and check the mechanical resistance.
The most common root causes: the connector not fully seated, moisture and oxidation inside the connector, a chassis connection taken from a painted or rusty surface, a loose battery terminal.
Always make the chassis connection to clean, sanded metal with a serrated washer. The LFT20 set comes with a single plug-in illuminated switch and the set is supplied with 2 supply cables.
The full topic: Converting a tractor hydraulic lever to electronic control