The motor does not run at all when I press the switch, what should I do?
Measure four things in order: battery voltage (typically 13.8–14.4 V while running), the integrity of the fuse, the voltage at the unit's supply terminals and the resistance of the chassis connection. If 12V is present at the supply terminals but the motor does not turn, isolate the unit from the wiring loom and verify it with a bench test by touching the wires directly to the battery.
Work by splitting the system in two: is the problem in the supply or in the unit?
- Battery: With the engine running there should be typically 13.8–14.4 V at the battery terminals. Values falling below 12 V with the ignition off point to a weak battery.
- Fuse: Do not judge by eye, measure it. Oxidation in the fuse holder also cuts the current.
- Unit terminals: Measure the voltage at the unit's supply terminals while the switch is pressed. If there is no voltage, the problem is on the wiring, switch or connector side.
- Chassis: The resistance between the negative terminal and clean chassis should be almost zero. Paint, rust and a loose bolt are the most commonly overlooked causes.
- Bench test: Remove the unit, touch the red wire to the battery positive and the black wire to the battery negative terminal. If the motor turns in both directions the unit is sound and the fault is in the installation.
Make sure you have not connected the polarity the wrong way round; the system takes 12V negative chassis. If these steps get you nowhere, contact technical support with your measured values.
Full topic: Converting a tractor hydraulic lever to electronic control