332-4911A2 Switch Box Power Pack for Mercury Mariner | JLM Marine

Switch Box Power Pack – Fits Mercury Mariner 20HP & 40HP (1972-1977)

This aftermarket switch box power pack is designed as a direct replacement for Mercury Mariner 20HP and 40HP outboard engines manufactured between 1972 and 1977. Engineered with high-quality plastic materials, this unit ensures maximum strength, durability, and long-lasting performance in demanding marine environments.

This switch box replaces multiple OEM part numbers including 332-4911A2, 332-4911A3, 332-4911A5, 332-4911A8, 338-4733A2, and aftermarket equivalent 18-5786, providing broad compatibility across the specified engine range.

• Direct replacement for original switch box – plug-and-play installation
• High-quality plastic construction for enhanced durability and longevity
• Comprehensive cross-reference coverage for easy identification

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here's a guide to help you identify your engine's serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

Your order includes:

• 1 x Switch Box Power Pack

Note: The package contains all parts shown in the product images.

Installation Guide

1. Disconnect the battery: Always disconnect the negative terminal before working on any electrical components to prevent accidental shocks or shorts.
2. Locate the existing switch box: Identify the original switch box power pack on your Mercury Mariner engine, typically mounted near the powerhead.
3. Disconnect wiring harness: Carefully disconnect all wiring connectors from the old switch box. Note the wire colors and positions for reference during reassembly.
4. Remove mounting hardware: Unbolt or unscrew the old switch box from its mounting bracket and remove it from the engine.
5. Position the new switch box: Place the new switch box in the same location and align the mounting holes with the bracket.
6. Secure the unit: Install the mounting bolts or screws and tighten securely, ensuring the switch box is firmly seated.
7. Reconnect wiring harness: Attach each wire connector to the corresponding terminal on the new switch box, matching wire colors and positions noted earlier.
8. Double-check connections: Ensure all electrical connections are secure and properly seated to prevent intermittent issues.
9. Reconnect the battery: Reconnect the negative battery terminal.
10. Test the engine: Start the engine and verify proper operation. Check for smooth ignition, consistent running, and absence of misfires.

Troubleshooting & FAQ

Q: How do I confirm this switch box fits my Mercury Mariner engine?
A: Verify your engine's HP rating (20HP or 40HP) and year (1972-1977). Cross-reference your original part number with the list provided above (332-4911A2, 332-4911A3, 332-4911A5, 332-4911A8, 338-4733A2, or 18-5786). You can also use the Mercury Serial Number Guide linked above to identify your engine model.

Q: What are the signs that my switch box needs replacement?
A: Common symptoms include difficulty starting the engine, rough idling, inconsistent spark, misfiring at certain RPMs, or complete loss of ignition. If you've ruled out spark plugs, coils, and stator issues, the switch box is often the culprit.

Q: Can I install this switch box myself or do I need a professional?
A: If you have basic mechanical skills and are comfortable working with electrical components, installation is straightforward—disconnect the battery, remove the old unit, and reconnect the wiring. However, professional installation is recommended to ensure proper setup and avoid electrical issues.

Q: What's the difference between this aftermarket switch box and the OEM version?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.
• Measurement tolerance: Please allow 1-3mm difference due to manual measurement (1cm = 10mm = 0.39 inch).

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.