The three failure families

Tilt/trim complaints sort into: electrical (nothing happens, or clicking), hydraulic (motor runs but no movement, or it leaks down), and mechanical (bent, seized, or leaking rams). Identify the family first.

Nothing happens / just a click

1. Check the battery and the trim circuit fuse/breaker — trim motors pull hard and expose weak batteries and corroded terminals first.
2. Listen at the relays (usually under the cowl). Swap the identical up/down relays as a quick test where applicable.
3. Test for voltage at the trim motor leads while pressing the switch (blue/green wiring is a common convention — verify with the wiring diagram). Voltage present but no motor = failed trim motor or corroded internal brushes.
4. Don't forget the switch itself — helm and cowl-mounted switches corrode; test both if fitted.

Motor runs, engine doesn't move

• Low fluid: check the reservoir with the engine in the position specified in the service manual (up or down varies by brand — checking in the wrong position gives a false reading).
• Air in the system after fluid loss: fill and cycle repeatedly to purge.
• Failed pump coupler or internal valve body — quote the unit if fluid and purge don't fix it.

Leaks down overnight / won't hold trim underway

• External wetness on the rams = shaft seals; rebuild or replace rams.
• Dry outside but sinks = internal valve leakage — usually a unit replacement or professional reseal.
• Trapped trim (won't tilt for towing): use the manual release valve (small slotted screw on the assembly — open per the manual, and close it firmly after).

Common mistakes

• Condemning the trim motor when the real issue is a corroded ground or a nearly dead battery
• Checking fluid at the wrong tilt position and overfilling
• Working under a raised engine without a support — never trust hydraulics or the tilt lock alone; block the engine or use a solid support before putting hands under it
• Mixing fluid types; use what the service manual specifies

When to walk away

Severe corrosion where the trim assembly bolts into the transom bracket can make removal destructive. On old salt-water engines, quote exploratory time honestly — seized trim units sometimes only come out in pieces.

Safety: support the engine mechanically before any work underneath; disconnect the battery before unplugging trim wiring — those leads are often unfused and live.