858740T4 Mercury Harness | Genuine Used Part

🔧 Product Description

Genuine Mercury Harness Assembly - Part Number: 858740T4

A genuine Mercury harness assembly used as an adapter harness in Mercury to Yamaha-style rigging / electrical conversion applications. This harness links compatible Mercury engine or control-system connectors to the matching Yamaha-style connection layout where the 858740T4 harness is specified.

⚙️ Key Features

• Genuine Mercury harness assembly

• Correct Mercury part number 858740T4

• Adapter harness for Mercury to Yamaha-style connection applications

• OEM Mercury factory harness assembly

• Fitment depends on plug type, engine rigging and control-system layout

🔄 Supersession & Cross Reference

OEM Supersession Chain:

• 858740T4 current / listed Mercury harness assembly reference

OEM / Related Numbers:

• 858740T4

• 84-858740T4

• 858740

• Mercury to Yamaha adapter harness reference

• Related rigging harness family reference

Aftermarket / Verified Equivalents:

• No aftermarket equivalent

🚤 Compatibility

Commonly used on:

• Mercury to Yamaha adapter harness installations

Typically suits:

• Engine / rigging applications:

• Mercury engine installations requiring Yamaha-style adapter connection

• Mercury 14-pin to Yamaha-style rigging conversion applications where 858740T4 is specified

• Mercury remote-control or instrumentation conversion setups using 858740T4

• Mercury / Yamaha shared rigging interface applications matched by plug layout

• HP Range: rigging-dependent

• Engine Type: Mercury outboard rigging harness system

• System Type: Adapter harness assembly

• Serial Note: Harness fitment is plug- and rigging-specific. Match by exact engine serial number, control type, connector count and pin layout.

🔌 Function

The harness adapts electrical control or instrumentation circuits between compatible Mercury and Yamaha-style plug systems.

Common signs of failure:

• No communication between control harness and engine

• Intermittent gauge or warning function

• Trim, start or key-switch circuit not operating

• Corroded or damaged pins

• Broken wire continuity inside harness

• Fault changes when harness is moved

• Incorrect adapter harness fitted to rigging system

📦 Condition

• Genuine used part

• Removed from running engine where applicable

• In good working condition unless otherwise stated