339-7452A3 Mercury Switch Box | Genuine Used Part

🔧 Product Description

Genuine Mercury Switch Box / CDI Module - Part Number: 339-7452A3

A genuine Mercury switch box / CDI ignition module used on selected Mercury and Mariner two-cylinder two-stroke outboards. This capacitor discharge ignition pack controls spark triggering from the stator and trigger circuits to the ignition coils.

⚙️ Key Features

• Genuine Mercury switch box / CDI module

• Correct Mercury part number 339-7452A3

• Used on selected 18HP, 20HP, 25HP, 35HP and 40HP two-cylinder Mercury / Mariner engines

• Cross-references with CDI Electronics 114-7452A3

• Also crosses with Sierra 18-5776 and Mallory 9-25101 style replacements

🔄 Supersession & Cross Reference

OEM Supersession Chain:

• 339-7452A3 Mercury switch box reference

• 339-7452A2 earlier related Mercury switch box reference

• 339-7452A1 earlier related Mercury switch box reference

OEM / Related Numbers:

• 339-7452A3

• 3397452A3

• 7452A3

• 339-7452A2

• 3397452A2

• 7452A2

• 339-7452A1

• 3397452A1

• 7452A1

• 899883230

• Switch box

• CDI module

• Capacitor discharge ignition pack

• Ignition switch box

Aftermarket / Verified Equivalents:

• CDI Electronics: 114-7452A3

• Sierra: 18-5776

• Mallory: 9-25101

🚤 Compatibility

Commonly used on:

• Mercury / Mariner two-cylinder two-stroke CDI ignition systems

Typically suits:

• Engine models:

• Mercury 18HP 2-cylinder two-stroke - 1980-1987

• Mercury 20HP 2-cylinder two-stroke - 1980-1987

• Mercury 25HP 2-cylinder two-stroke - 1980-1987

• Mercury 35HP 2-cylinder two-stroke - 1980-1987

• Mercury 40HP 2-cylinder two-stroke - 1980-1987

• Mariner 18HP 2-cylinder two-stroke - 1980-1987

• Mariner 20HP 2-cylinder two-stroke - 1980-1987

• Mariner 25HP 2-cylinder two-stroke - 1980-1987

• Mariner 35HP 2-cylinder two-stroke - 1980-1987

• Mariner 40HP 2-cylinder two-stroke - 1980-1987

• HP Range: 18HP - 40HP

• Engine Type: Mercury / Mariner two-cylinder two-stroke outboard CDI ignition system

• Year Range: approximately 1980 - 1987

• Serial Note: Match by exact Mercury / Mariner serial number, original switch-box number, wiring colours, connector style and ignition-system diagram before installation.

🔌 Function

The switch box receives stator and trigger inputs, stores ignition energy and fires the ignition coils at the correct timing point.

Common signs of failure:

• No spark on one or both cylinders

• Weak or intermittent spark

• Engine starts then loses spark

• Misfire under load

• Heat-related ignition failure

• Kill circuit or stop wire fault damaging the module

• Spark returns when a known-good switch box is fitted

• Burnt, cracked or corroded switch-box terminals

📦 Condition

• Genuine used part

• Removed from running engine where applicable

• In good working condition unless otherwise stated