When outboard power trim stops working, the fault is usually electrical: a blown fuse or tripped breaker, a weak battery, a failed trim switch, a stuck relay or a worn pump motor. If the pump runs but the motor does not move, the hydraulic side is the problem: low fluid, an open manual release valve or worn seals. A motor that will not stay up points to the release valve or internal leaks.
Diagnose by symptom
| Symptom | Likely cause |
|---|---|
| Nothing happens, no click | Fuse, breaker, battery, switch or wiring |
| Relay clicks but the pump does not run | Pump motor, motor brushes or a bad ground |
| Trims down but not up (or the reverse) | One relay or one side of the switch |
| Pump runs but the motor does not move | Low fluid or the manual release valve open |
| Motor slowly drops after trimming up | Manual release valve not closed, or internal seal leak |
| Trim works but the gauge does not | Trim sender or gauge wiring |
Check the simple things first
- Charge or test the battery; trim motors draw high current and fail on weak batteries.
- Check fuses and breakers and the main connections at the battery.
- Try the switch on the engine cowl and the one on the control; if one works, the other switch or its wiring has failed.
- Listen for the relays clicking.
- Check that the manual release valve is fully closed.
- Check the fluid level in the reservoir with the motor tilted fully up, using the fluid the manufacturer specifies.
Relays and the pump motor
Swapping the up and down relays, where they are identical, is a quick test: if the fault moves to the other direction, replace the relay. A pump motor that only runs when tapped has worn brushes or a failing armature and usually needs rebuilding or replacing.
Hydraulic problems
Low fluid often comes from a leaking seal on a trim ram. Look for oily residue on the rams and the transom bracket. Air in the system after topping up is bled by running the trim fully up and down several times.
Trim and tilt that work only some of the time
Intermittent trim usually means a poor connection: corroded terminals at the relays, a loose ground or a chafed wire where the harness bends as the motor turns and tilts. Clean and seal the connections with dielectric grease, and check the harness at every pivot point. Salt water speeds up this corrosion, so inspect more often on boats used in the ocean.
Why trim matters
Trim sets the running angle of the boat. Without it, the boat may porpoise or struggle to plane; see boat porpoising and boat won’t get on plane. For general upkeep see outboard motor maintenance, and for a repower see our outboard motors.
More guides: tilt and trim fluid · outboard steering cable · outboard trim sender and gauge.
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