878492T14 Mercury Junction Box J-Box | Genuine Used Part

🔧 Product Description

Genuine Mercury SmartCraft Junction Box - Part Number: 878492T14

A genuine Mercury SmartCraft junction box used as a CAN bus connection point in Mercury, MerCruiser and Mariner SmartCraft rigging systems. This J-box connects SmartCraft gauges, VesselView displays, engine harnesses, terminators and accessory harnesses.

⚙️ Key Features

• Genuine Mercury SmartCraft junction box
• Correct Mercury part number 878492T14
• 4-way SmartCraft J-box reference
• Superseded to 8M0165557 service kit
• Used in SmartCraft CAN bus gauge and accessory networks

🚤 Compatibility

Commonly used on

• Mercury / MerCruiser / Mariner SmartCraft CAN bus rigging systems

Typically suits

• Engine models:
• Mercury 200XS DFI 2.5L - serial 1E000797 to 1E002110
• Mercury 225 Sport XS - serial 1E002584 and up
• Mercury 225 XS - serial 1E002584 and up
• Mercury 250 Sport XS - serial 1E002342 to 1E051823
• Mercury 250 Sport XS - serial 1E051824 to 1E052994
• Mercury 250XS 3.0L DFI - serial 1E000797 to 1E002341
• Mercury 250XS 3.0L DFI - serial 1E002342 to 1E051113
• Mercury 250XS 3.0L DFI - serial 1E053158 and up
• Mercury 3.0L DSI - serial 1E052967 and up
• Mercury 300XS 3.2L DFI - serial 1E001867 to 1E052057
• Mercury 300XS 3.2L DFI - serial 1E052058 and up
• Mercury JP 3.0L DFI - serial 1E003046 and up
• Mercury SmartCraft outboard installations using 10-pin CAN harnesses
• MerCruiser SmartCraft sterndrive and inboard installations using SmartCraft J-box networking
• HP Range: SmartCraft network component used across SmartCraft-equipped engines
• Engine Type: Mercury / MerCruiser / Mariner SmartCraft CAN bus system
• Year Range: Serial-number controlled by SmartCraft rigging diagram
• Serial Range: Confirmed DFI performance serial ranges listed above; final fitment must be checked by engine serial number and SmartCraft harness layout.

🔌 Function

The junction box provides a CAN bus connection point so SmartCraft gauges, VesselView displays, harnesses and accessories can communicate with the engine network.

⚠️ Common Signs of Failure

• SmartCraft gauges not powering up or not communicating
• VesselView display losing engine data
• Intermittent CAN bus connection faults
• Corroded or damaged J-box pins
• Missing weather caps causing water ingress
• Network fault isolated to the junction box
• Accessories work when connected through a known-good J-box

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 8M0165557 → Supersedes 878492T14
• 8M0165557 → Supersedes 878492K14
• 8M0165557 → Supersedes 878492K16
• 878492T14 earlier SmartCraft junction box reference
• 878492K14 earlier SmartCraft junction box kit reference
• 878492A14 earlier SmartCraft junction box kit reference
• 878492B14 related SmartCraft junction box reference
• 878492T16 related SmartCraft junction box reference
• 878492K16 related SmartCraft junction box kit reference

OEM / Related Numbers

• 878492T14
• 878492-T14
• 878492K14
• 878492A14
• 878492B14
• 878492T16
• 878492K16
• 8M0165557
• 98-8M0165557
• 859318B2 weather cap assembly
• 8M0210752 weather cap assembly
• 859318T1 terminator / harness reference
• 8M0210753 terminator reference
• 84-879982T20 SmartCraft harness

Aftermarket / Verified Equivalents

• FASWORX: SmartCraft 4-port junction box
• OMGparts: SmartCraft 4-port junction box

📦 Condition

• Genuine used part
• Removed from running engine where applicable
• In good working condition unless otherwise stated