ARCO is an original-equipment electromechanical solenoid that replaces Mercury’s 89-68258 A4 family of trim, tilt, and starter relays. On Mercury Marine, Mercury Racing, and Mariner outboards, this device serves as the switching interface between the low-current control signal from trim, tilt, or lift switches and the high-current requirements of the pump motor or starter motor. These circuits regularly operate in the 80–120 amp load range on Mercury V6 outboards, including the Black Max era, 2.5 EFI, XR4, XR6, 150 XR6, 175 EFI, 200 HP, 260 EFI, 280 ROS outboards.
Its function is to close the power circuit when the coil is energized. If the coil fails to pull the plunger, the high current never transfers across the contacts. When this device ages or becomes internally resistive, the field symptom is often a single, clean click with no trim movement, or a click with no crank response.
This solenoid family was used extensively in the Mercury 2.0L, 2.4L, and 2.5L V6 outboards from the 1980s through the late 1990s. It also appears in a range of MerCruiser sterndrive trim pump relay circuits, including common Alpha and Bravo trim systems. In practice, this part is repeatedly visible in mid-generation Mercury rigging manuals, factory service manuals, and wire prints for 135 HP, 150 HP, 175 HP, and 200 XRi outboards.
Because trim and tilt functions cycle frequently during real operation, this solenoid experiences a duty cycle higher than most other switching devices in the boat. Its failure rate is therefore expected to be above average. It is common to encounter units that pass a bench trigger test but fail intermittently under load. Technicians routinely replace these during electrical cleanup on older Mercury V6 carb, EFI, and 2.5 Laser EFI motors.
Mercury superseded this solenoid multiple times. Aftermarket catalogs therefore list numerous superseded numbers that all converge to this same functional component. ARCO’s approach is to provide one stable OE-quality replacement that matches the original electrical characteristics.
Cross reference examples include F460917-1, 15857, 18-5815, 61053, 68258, 68258A4, 68258B4, 72370, 76545, 76545T, 853654A1, 853654B1, 9-15111, and OEM 89-68258A4.
In field diagnostics, if solid 12V is present at the battery lug of the solenoid during the command event, the coil is receiving a control trigger, and the output side does not rise to battery level, the fault is very often internal to the solenoid. That is the direct chain of evidence that leads to replacement.
This solenoid does not resolve mechanical pump binding, failed starter brushes, rotted cables, or insufficient battery energy. It resolves the specific failure mode where the logic-level command exists, the coil responds, but the heavy current path does not close.
Includes one (1) Arco Solinoid with nuts and washers as pictured.
Contact Mike Hill at +1-714-697-1716 or email mike@buckshotracing77.com for technical support.