Keeping your Johnson or Evinrude outboard running smoothly means staying on top of those electrical components that take a beating from saltwater spray and constant vibration. The Sierra 18-5705 power trim relay steps in as a reliable fix when your trim system starts acting up, ensuring effortless control over your engine's tilt and trim for safer, more enjoyable boating trips.

Why Your Outboard Needs a Dependable Trim Relay

Picture this: you're out on the water, wind picking up, and your motor won't tilt up or down properly. That's often the relay at fault. This 12-volt, 5-terminal single-pull double-throw relay handles the high current demands of the power trim pump without flinching. It's engineered to OEM specs, so it slots right into place on most Johnson and Evinrude models from the 1970s through the early 2000s, restoring precise hydraulic control.

Boaters swear by replacements like this because factory relays corrode from moisture ingress or burn out from overloads during heavy use. Swapping it out prevents bigger headaches, like stuck motors or strained hydraulics, keeping your adventures uninterrupted.

Standout Features for Reliable Performance

• 5-Terminal Design: Matches factory wiring harnesses for plug-and-play simplicity.
• Single Pull, Double Throw (SPDT): Switches power efficiently between up and down circuits.
• 12-Volt Rating: Perfect for standard outboard electrical systems.
• Durable Construction: Sealed contacts resist corrosion, vibration, and heat—common killers in marine environments.
• Direct OEM Replacement: No modifications needed, saving you time and frustration at the dock.

Perfect Fit for Johnson and Evinrude Outboards

This relay shines across a wide range of V4, V6, and inline models. Think classic 88-150 HP engines where trim issues pop up frequently after years of service. It's a go-to for owners maintaining older OMC powerheads, ensuring compatibility without guesswork. Always cross-check your wiring diagram, but most setups from the carbureted era onward pair seamlessly.

Easy DIY Installation Tips

No need for a marine mechanic—handle this in under 30 minutes with basic tools:

1. Power down: Disconnect the battery to avoid shorts.
2. Locate the relay: Usually mounted near the trim pump or in the engine's electrical box.
3. Unplug and inspect: Note any burnt terminals or green corrosion.
4. Swap it in: Secure the new Sierra unit, double-check connections (typically labeled for up/down/ground/power).
5. Test thoroughly: Cycle the trim in water or on a hose to confirm smooth operation.

Pro tip: Coat terminals with dielectric grease post-install to fend off future moisture woes.

Troubleshooting Trim System Woes

Before replacing, rule out other culprits:

• No trim up/down: Check fuses, battery voltage, and pump motor first.
• Intermittent action: Relay contacts often pit from arcing—clean or replace.
• One direction only: SPDT failure is common; this relay fixes it reliably.
• Overheating: Undersized wiring? Upgrade while you're in there.

Regular checks during off-season storage can extend life—spray contacts and inspect for rodent nibbles if trailered.

The Sierra Difference: Marine-Grade Trust

Sierra doesn't cut corners like some budget parts. Their relays undergo rigorous testing for amp draw, endurance cycling, and saltwater exposure. Boaters report years of trouble-free service, even in harsh brackish conditions. It's about peace of mind—knowing your trim won't fail when you need full control backing off a trailer or fighting choppy wakes.