Mercury - Starter or Power Trim Solenoid Electrical System Stepped Mounting Plate 8M0185622. Overview. Any boater who's spent enough time on the water knows the value of a dependable start and a responsive trim system. Those simple moments - tapping the trim to lift the bow or turning the key before heading out at first light - set the tone for the entire day. That's why this Mercury Marine part matters. It's built to deliver that steady, no-nonsense reliability you can feel, the kind that lets