Mercury - Remote Control 30 Foot Ignition and Engine Wiring Harness 84-896537K29. The Mercury Remote Control 30-Foot Wiring Harness is designed for installations that require a single, continuous wiring run between the helm and the outboard. Its full 30-foot length helps eliminate the need for multiple extensions and supports a cleaner, more organized rigging layout. This harness is commonly used on larger boats or installations with longer helm distances where a one-piece solution simplifies ro