Sierra MP39800 Marine Ignition Starter Switch – 4-Position, Conventional, 12V/15A
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Sierra MP39800 Marine Ignition Starter Switch – 4-Position Conventional, 12V/15A
The Sierra MP39800 is a heavy-duty marine ignition starter switch built for conventional ignition systems that require an Accessory position. The 4-position action — Accessory, Off, Ignition, and Start — lets you power onboard electronics independently before engaging the ignition, a feature increasingly common on modern helm setups with chartplotters, VHF radios, and stereo systems. A corrosion-resistant polyester housing with an inner seal between the cylinder lock and contact plate keeps moisture out and prevents shorts in demanding marine environments.
The 1-1/8" cylinder diameter and 7/8" mounting hole fit a wide range of marine dash panels. The 4-blade terminal layout suits conventional ignition wiring with an accessory circuit. Note: this switch does not include a push-to-choke function or a boot.
Key Specifications
- Part Number: 11-MP39800
- Switch Type: 4-Position (Accessory – Off – Ignition – Start)
- Ignition Type: Conventional
- Voltage: 12V DC
- Current Rating: 15A
- Solenoid: 30A
- Cylinder Diameter: 1-1/8"
- Mounting Hole: 7/8"
- Terminals: 4 Blade
- Housing Material: Polyester (corrosion-resistant)
- Push-to-Choke: Not included
- Boot: Not included
Compatible Applications
- Outboard and inboard engines with conventional ignition systems requiring an Accessory position
- Marine helm panels with chartplotters, VHF radios, or stereo systems needing independent accessory power
- Marine dash panels with a 7/8" mounting hole accepting a 1-1/8" cylinder switch
- 12V DC electrical systems requiring a 4-position Accessory/Off/Ignition/Start switch
- Direct replacement for worn or damaged OEM 4-position ignition switches on conventional-ignition engines
Parts Desk Insights
The MP39800 is the right choice when your helm has electronics — a chartplotter, VHF, or stereo — that you want to power up before cranking the engine. The Accessory position is the key upgrade over a standard 3-position switch. If you only need Off/Ignition/Start without an Accessory position, the Sierra MP39770 3-Position Conventional Switch (with boot) or the compact Sierra MP39780 3-Position Compact Switch are the simpler alternatives. For a 4-position switch in a smaller 5/8" cylinder format, the Sierra UN12140 Compact 4-Position Switch covers that application. If you need a 4-position switch with screw terminals rather than blade terminals, the Sierra MP41040 4-Screw Terminal Switch is the direct alternative in the same 1-1/8" format.
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.