Mercury - Trim Sensor Kit Digital Trim Angle Feedback 863187A2. Overview. Most boaters go years without thinking about their trim sensor. It just sits there doing its job-quiet, steady, and taken for granted. But when the readings stop lining up, you feel it right away. The bow does one thing, the gauge shows another, and the whole ride loses a bit of its rhythm. The Mercury Trim Sensor Kit (863187A2) brings that rhythm back. It gives you clean, honest trim information that feels right the momen