6 HP 8 HP 9.9 HP 10 HP 15 HP 20 HP 25 HP Mercury Mariner Outboard 2 Stroke CDI Switch Box 339-7452A19
PRODUCT DETAILS
CDI Unit / Power Pack / Switch Box for Mercury & Mariner Outboards
High-quality marine-grade aftermarket CDI ignition unit / power pack / switch box for selected Mercury and Mariner 6 HP, 8 HP, 9.9 HP, 10 HP, 15 HP, 20 HP and 25 HP 2-stroke outboard engines.
Designed for selected:
2 Cylinder – 2 Stroke – Bullet Connection
Mercury / Mariner outboards, primarily from approximately 1980–1997, depending on the exact engine and serial number.
Designed as a replacement for the Mercury / Quicksilver 339-7452A switch-box family, including:
339-7452A15 / 339-7452A19
Fits Selected Mercury / Mariner Outboards
6 HP
- 2 Stroke
- 2 Cylinder
- Selected applications
- Bullet-connection switch box
8 HP
- 2 Stroke
- 2 Cylinder
- Selected applications
- Bullet-connection switch box
9.9 HP
- 2 Stroke
- 2 Cylinder
- Selected applications
- Bullet-connection switch box
10 HP
- 2 Stroke
- 2 Cylinder
- Selected applications
- Bullet-connection switch box
Including selected:
- 10 HP
- 10 Magnum
- 10 Marathon
- 10 Sea Pro
depending on serial number and specification.
15 HP
- 2 Stroke
- 2 Cylinder
- Selected applications
- Bullet-connection switch box
Including selected standard, Marathon / Sea Pro / Super 15 applications depending on serial number.
20 HP
- 2 Stroke
- 2 Cylinder
- Selected applications
- Bullet-connection switch box
Also used on selected 20 Jet applications depending on serial number.
25 HP
- 2 Stroke
- 2 Cylinder
- Selected applications
- Bullet-connection switch box
Including selected:
- 25 HP
- 25 Marathon
- 25 Sea Pro
depending on serial number and specification.
Fitment Summary
| HP | Engine | Cylinders | Connection |
|---|---|---|---|
| 6 HP | 2 Stroke | 2 | Bullet |
| 8 HP | 2 Stroke | 2 | Bullet |
| 9.9 HP | 2 Stroke | 2 | Bullet |
| 10 HP | 2 Stroke | 2 | Bullet |
| 15 HP | 2 Stroke | 2 | Bullet |
| 20 HP | 2 Stroke | 2 | Bullet |
| 25 HP | 2 Stroke | 2 | Bullet |
Approximate Application Period
1980–1997
The exact production period varies according to horsepower, market and engine serial number.
⚠️ Do not use the year range alone to determine compatibility.
Replaces Mercury / Quicksilver Part Numbers
- 339-7452A1
- 339-7452A3
- 339-7452A7
- 339-7452A8
- 339-7452A9
- 339-7452A10
- 339-7452A11
- 339-7452A14
- 339-7452A15
- 339-7452A18
- 339-7452A19
- 339-7452A20
- 339-7452A21
Additional Cross References
- CDI Electronics 114-7452K1
- Sierra 18-5777
- Sierra 18-5778
OEM manufacturer names and part numbers are provided for identification and compatibility reference only.
⚠️ VERY IMPORTANT – BULLET CONNECTION TYPE
This CDI / switch box is for selected Mercury / Mariner engines using the:
BULLET-WIRE CONNECTION PACK
Please check your existing CDI connections BEFORE ordering.
Mercury used different versions of the switch box.
Some engines use:
Bullet-wire connections
while others use:
Nut / Stud / Bolted wire connections
These are not the same ignition unit.
Bullet vs Stud Connection
Before ordering, look carefully at your original switch box.
This Listing
Bullet Connection Type
The applicable wires connect using individual bullet-style electrical connectors.
Different Version
Some Mercury / Mariner engines use a switch box with nut / stud-type connections.
If your original switch box uses the different stud / nut connection arrangement, please do not order this unit simply because the horsepower and year appear correct.
⚠️ IMPORTANT – Check Before Ordering
Please do NOT order by horsepower, year or appearance alone.
Mercury and Mariner used different ignition systems depending on:
- Engine horsepower
- Model
- Production year
- Complete serial number
- Number of cylinders
- Ignition-system specification
- Original switch-box part number
- Wiring connection type
For the safest identification, check your original switch box for one of the 339-7452A numbers listed above.
What Is a CDI / Switch Box?
The switch box is an important part of the Mercury / Mariner CDI ignition system.
It receives electrical signals from the stator and trigger system and controls the ignition output to the ignition coils.
A faulty CDI / switch box can be associated with symptoms such as:
- No spark
- Intermittent spark
- Loss of spark on one cylinder
- Difficult starting
- Engine cutting out
- Misfiring
- Loss of ignition when hot
- Irregular engine operation
Important
These symptoms do not automatically mean the switch box is faulty.
Similar symptoms can be caused by the stator, trigger, ignition coils, stop circuit, wiring or poor electrical connections.
Proper diagnosis is recommended before replacing the CDI.
Product Features
- Marine-grade aftermarket CDI unit
- CDI ignition module
- Power pack
- Switch box
- Suitable for selected Mercury outboards
- Suitable for selected Mariner outboards
- 6 HP
- 8 HP
- 9.9 HP
- 10 HP
- 15 HP
- 20 HP
- 25 HP
- 2 Stroke
- 2 Cylinder
- Bullet-wire connection type
- Replacement for 339-7452A family
- Direct replacement for compatible applications
- No assembly required
- New aftermarket ignition component
⚠️ Appearance Does Not Confirm Fitment
If the CDI looks the same as the one fitted to your engine, this does not always mean it is the correct part for your outboard.
Different Mercury / Mariner switch boxes can look very similar externally but have different wiring arrangements and electrical specifications.
Please check:
- Original CDI part number
- Complete engine serial number
- Number of cylinders
- Wire connections
- Bullet vs stud / nut connections
- Mounting arrangement
If you are unsure, contact SSI Marine before purchasing.
Before Replacing Your CDI / Switch Box
If your engine has an ignition problem, we recommend checking the complete ignition system before fitting a replacement CDI.
Check:
- Stator output
- Trigger output
- Ignition coils
- Spark plugs
- Spark plug leads
- Stop / kill circuit
- Engine earth / ground connections
- CDI wiring
- Electrical connectors
- Burnt or corroded terminals
- Damaged or melted wiring
A fault elsewhere in the ignition system can produce symptoms similar to a failed switch box and may damage a replacement component.
Aftermarket Replacement Part
This is a high-quality marine-grade aftermarket replacement part.
It is not a genuine Mercury, Mariner or Quicksilver component.
OEM manufacturer names and part numbers are provided for identification and compatibility reference only.
The component is designed as a replacement for compatible Mercury / Mariner applications using the 339-7452A switch-box family.
Buyer Responsibility
It is the buyer's responsibility to confirm compatibility before purchasing.
Please check:
- Engine horsepower
- 2-stroke engine
- 2-cylinder configuration
- Complete serial number
- Original switch-box part number
- Bullet-wire connections
If you are unsure, please send SSI Marine:
Engine horsepower + complete serial number + clear picture of your existing CDI and connections
Our technical team will be happy to help identify the correct unit.
Why Buy From SSI Marine?
- Marine-grade aftermarket & OEM-spec parts
- Workshop-tested products
- More than 10 years supplying and working with outboard engines
- Same-day dispatch before 1 PM Monday–Friday
- Royal Mail Tracked 24
- UK stock
- Collection available from Leigh, Greater Manchester
- Technical support from experienced outboard specialists
- Workshop open Monday–Friday, 9 AM–5 PM
SHIPPING & DELIVERY
Delivery & Returns Policy
Delivery
Standard Delivery
- £6: Royal Mail Tracked 24 Service
- £3.99: Large Letter - Royal Mail 1st Class Post (Untracked)
We offer free delivery on all orders over £150 (excludes outboard engines).
Orders placed before 1:00 PM (Monday-Friday) are usually dispatched the same working day.
Most parcels are delivered within 24 hours, but please allow extra time for courier delays that may occur outside our control.
For outboard engines, please contact us for a delivery quote.
Important: Please ensure your shipping address is correct before completing checkout. SSI Marine is not responsible for parcels sent to an incorrect address provided by the buyer.
Tracking Your Order
Once your order has been dispatched, you will receive a tracking number via email (after 5 PM on the day of dispatch).
Tracking is available only for parcels sent via Royal Mail Tracked 24.
Large Letter orders are sent via Royal Mail 1st Class Post (untracked).
Returns
We accept returns of unused and undamaged items within 30 days of purchase.
Returned items must be in sellable condition and include the original packaging.
Please do not tape, label, or write directly on the product's original box.
Important: Do not return items in their original product boxes only, they must be placed inside a protective outer box or bag. Parcels returned like the example below will be subject to a 20% restocking fee.
Return shipping costs are the customer's responsibility.
Please include your order details and reason for return inside the parcel.
Refunds
Refunds are issued for the item purchase price only (shipping costs are non-refundable).
All refunds will be made using the same payment method as your original order.
Items returned in poor condition or without proper packaging may incur a 20% restocking fee.
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