An outboard trim sender is a small sensor on the engine’s mounting bracket that measures the engine’s trim angle and sends it to the trim gauge. If the gauge reads wrong, check the sender’s adjustment first, then its resistance as the engine trims up and down, then the wiring and the gauge’s power and ground. On many engines the sender can be rotated in its slotted mounting holes to set the gauge to read fully down when the engine is fully trimmed in.
What the trim sender does
The sender is a variable resistor driven by the engine’s swivel bracket. As the engine trims out, its resistance changes and the gauge needle moves. On some engines a second sender or switch limits how far the engine can trim at speed, or sets a trailering limit. Newer engines with digital displays may read trim through the engine’s network instead of a separate gauge circuit.
Trim gauge not working: what to check
- Gauge reads full or empty all the time. An open or shorted sender, a broken wire or a missing gauge ground.
- Gauge reads but is off. The sender needs adjusting or the gauge and sender are not matched.
- Gauge jumps around. A worn sender track or corroded connection.
- Gauge dead with other gauges working. Check its power, ground and lighting connections at the back of the gauge.
Testing the sender
Disconnect the sender’s lead and measure its resistance to ground, or between its two leads, as you trim the engine through its range. The reading should change smoothly with no dropouts. Compare the values with the service manual for your engine, since senders from different makers use different ranges.
Adjusting the gauge
- Trim the engine fully down.
- Loosen the sender’s mounting screws.
- Rotate the sender until the gauge reads its lowest mark, then tighten the screws.
- Trim up and down to confirm the gauge follows the engine.
Engines with digital displays often calibrate trim through the display’s settings menu instead.
Replacing a trim sender
Route the new sender’s wiring along the old one, away from moving parts and the trim rams, and seal the connections against water. Use the sender made for your engine and gauge, since resistance ranges differ.
Related
If the engine will not trim at all, see outboard trim not working and tilt and trim fluid. For other gauges, see outboard tachometers. Browse engines on outboard motors.
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