Sierra MP39040 Marine Ignition Starter Switch – 3-Position, Magneto, Brass, 12V/10A
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Sierra MP39040 Marine Ignition Starter Switch – 3-Position Magneto, Brass, 12V/10A
The Sierra MP39040 is a traditional brass-bodied marine ignition starter switch built for magneto ignition systems. Solid brass construction delivers time-tested corrosion resistance with a premium look and feel that suits classic and vintage marine helm panels. The 3-position action — Off, Ignition, and Start — provides clean, positive control over engine startup and shutdown, backed by a 30A solenoid rating.
The 1-1/8" cylinder diameter and 7/8" mounting hole fit a wide range of marine dash panels, and the included boot provides a finished, weather-resistant installation. The 5-screw terminal layout accommodates standard magneto ignition wiring. Note: this switch does not include a push-to-choke function, and is rated at 10A — verify your circuit load before installation.
Key Specifications
- Part Number: 11-MP39040
- Switch Type: 3-Position (Off – Ignition – Start)
- Ignition Type: Magneto
- Voltage: 12V DC
- Current Rating: 10A
- Solenoid: 30A
- Cylinder Diameter: 1-1/8"
- Mounting Hole: 7/8"
- Terminals: 5 Screw
- Housing Material: Brass (traditional corrosion-resistant construction)
- Includes: Boot
- Push-to-Choke: Not included
Compatible Applications
- Outboard and inboard engines with magneto ignition systems
- Classic, vintage, and traditional-style marine helm panels
- Marine dash panels with a 7/8" mounting hole accepting a 1-1/8" cylinder switch
- 12V DC circuits with loads at or below 10A
- Direct replacement for worn or damaged OEM brass ignition switches on magneto-equipped engines
Parts Desk Insights
The MP39040 is the right choice when you want a brass-bodied switch for a classic or vintage helm, or when you're matching an existing brass switch on the panel. The traditional brass construction is its defining feature — but note the 10A current rating, which is lower than the polyester alternatives in this family. If your circuit load exceeds 10A or you need push-to-choke, the Sierra MP39760 Magneto Polyester Switch is the higher-rated (15A) alternative with push-to-choke included. For a magneto switch with a 5-screw terminal layout in polyester at 15A, the Sierra MP39100 Polyester Ignition Switch is the direct upgrade. If your engine runs a conventional ignition rather than magneto, the Sierra MP39770 Conventional Ignition Switch is the correct fit.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.