# 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• Superseded to 8M0165557 service kit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

  

🔄 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

  

🚤 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

  

📦 Condition

  

• Genuine used part

• Removed from running engine where applicable

• In good working condition unless otherwise stated

## Details

- **Price:** 62.5 AUD
- **Vendor:** Sawley's Auto and Marine
- **Tags:** Sawley’s AAM Used Parts – Electronic Components | ECU CDI & Electrical Parts

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 62.50 AUD | In stock |

## Images

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

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/878492t14-mercury-junction-box-j-box-genuine-used-part)
> Updated: 2026-06-29