What is the problem if the motor turns in one direction and does not come back?
Movement in one direction only shows that one side of the polarity-reversing control path is broken. The most common causes are a switch contact not making in one position, an oxidised or dislodged terminal inside a connector, and a single broken core in the wiring loom. If the motor turns when you reverse the wires in the bench test, the unit is sound.
On these kits, two-way movement is obtained by reversing the polarity of the voltage applied to the DC motor. If one direction works and the other does not, the circuit path for that direction is not being completed.
Order of checks:
- Bench test: Remove the unit, touch the supply wires to the battery, then reverse them and try again. If the motor turns in both directions, the unit is sound and the fault is on the switch/wiring side.
- Switch: Measure contact continuity in both positions. On an illuminated switch, the light coming on does not prove the contact is making.
- Connector: Separate the plug connection and look for oxidation, a pushed-back pin or damp on the terminals. In agricultural conditions this is the most common failure point.
- Wire: A single broken core may not be visible; measure continuity end to end. Look especially at points where the wire chafes on moving parts.
Rule out the mechanical possibility too: the lever may be driven one way by spring force while binding in the other direction. Disconnect the kit and move the lever by hand in both directions.
Full topic: Converting a tractor hydraulic lever to electronic control