338-4733A2 Mercury Switch Box | Genuine Used Part

🔧 Product Description

Genuine Mercury Switch Box / CDI Module - Part Number: 338-4733A2

A genuine Mercury switch box used on selected vintage Mercury and Mariner two-cylinder outboard ignition systems. This CDI module controls ignition triggering and coil firing where the original switch-box number, wiring layout and serial range match.

⚙️ Key Features

• Genuine Mercury switch box / CDI module

• Correct OEM part number 338-4733A2

• Cross-references with 332-4911A2, 332-4911A5 and 332-4911A8

• Used on selected Mercury / Mariner 20HP and 40HP two-cylinder outboards

• Match by serial range, wiring colours and ignition-system diagram

🔄 Supersession & Cross Reference

OEM Supersession Chain:

• 338-4733 Mercury switch box reference

• 338-4733A2 Mercury switch box reference

• 332-4911A2 related Mercury switch box reference

• 332-4911A5 related Mercury switch box reference

• 332-4911A8 related Mercury switch box reference

OEM / Related Numbers:

• 338-4733A2

• 3384733A2

• 338-4733

• 3384733

• 332-4911A2

• 3324911A2

• 332-4911A5

• 3324911A5

• 332-4911A8

• 3324911A8

• Switch box

• CDI module

• Ignition module

• Capacitor discharge ignition box

• Mercury 20HP / 40HP switch box

Aftermarket / Verified Equivalents:

• CDI Electronics: 114-4911

• Sierra: 18-5787

• Mallory: 9-25105

• Aftermarket replacement for 338-4733A2 / 332-4911A2 / 332-4911A5 / 332-4911A8

🚤 Compatibility

Commonly used on:

• Mercury / Mariner 20HP and 40HP vintage CDI ignition systems

Typically suits:

• Engine models:

• Mercury 20HP Model 200 - 1973-1977, serial 3537531 to 4709592

• Mercury 40HP Model 402 electric start - 1972-1974, serial 3336258 to 3859434

• Mercury 40HP Model 402 manual start - 1972-1974, serial 3336258 to 4117709

• Mercury 40HP Model 402 electric start - 1975-1977, serial 4117710 to 4860102

• Mercury 40HP manual start - 1975-1981, serial-controlled applications up to 5823917

• Mercury 40HP electric start - 1978-1981, serial 4860103 to 5823917

• Mercury / Mariner 20HP and 40HP ignition systems where the original switch box is 338-4733A2 or 332-4911A-series

• HP Range: 20HP - 40HP

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

• Year Range: approximately 1972 - 1981 depending on engine model and start type

• Serial Note: Match by exact Mercury / Mariner serial number, wiring colours, switch-box mounting, trigger/stator layout and original switch-box number before installation.

🔌 Function

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

Common signs of failure:

• No spark

• Weak or intermittent spark

• Spark on one cylinder only

• Hard starting

• Engine starts then loses spark

• Misfire under load

• Heat-related ignition failure

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

📦 Condition

• Genuine used part

• Removed from running engine where applicable

• In good working condition unless otherwise stated