Sierra Emergency Cut-Off Switch MP40970-1, 4-Terminal Selectable Circuit, White, with Coiled Lanyard

The Sierra MP40970-1 is an emergency cut-off switch (kill switch) built for boats that need a reliable engine-stop safeguard at the helm. If the operator is thrown from the seat or moves away from the control station, the attached lanyard pulls free of the switch and immediately interrupts the ignition circuit, shutting the engine down. This is a core piece of onboard safety equipment for anyone running an outboard or similarly equipped boat.

The switch is wired with 4 terminals, which lets it be configured for either a normally open or a normally closed circuit depending on how the boat's ignition system is set up. This flexibility means the same switch body can be installed across different wiring configurations rather than needing a dedicated part for each. It comes with its coiled lanyard attached and is finished in white to match common helm and dash hardware. Should the lanyard itself ever need replacing, Sierra's MP40990 lanyard is the correct replacement for this switch.

Sierra is a long-standing supplier of marine engine and ignition parts, and the MP40970-1 is sold as a direct part for boat owners and marine technicians replacing a worn or failed cut-off switch.

Specifications

• Brand: Sierra
• Manufacturer Part Number: MP40970-1
• Product Type: Emergency Cut-Off Switch
• Terminals: 4
• Circuit Type: Selectable, normally open or normally closed
• Color: White
• Replacement Lanyard: MP40990
• OEM Cross Reference: 722325
• Weight: 0.2 pounds
• Product Dimensions: 0.39 x 0.39 x 0.39 inches
• UPC: 808282200756
• National Stock Number: 5930-01-553-8353
• Country of Origin: United States

Fitment

Universal emergency cut-off switch application; no specific make, engine, or model fitment is specified for this part.

Replaces (OEM)

• 722325

Frequently Asked Questions

What does the Sierra MP40970-1 emergency cut-off switch do? It interrupts the ignition circuit and shuts the engine down when the attached lanyard is pulled free, acting as a safety kill switch if the operator leaves the helm unexpectedly.

Does the MP40970-1 come with a lanyard? Yes, the MP40970-1 emergency cut-off switch is supplied with a coiled lanyard attached.

Can this switch be wired for either a normally open or normally closed circuit? Yes, the MP40970-1 has 4 terminals so it can be configured for a normally open or a normally closed circuit depending on the boat's ignition wiring.

What replacement lanyard fits the MP40970-1? The MP40990 lanyard is the correct replacement lanyard for the MP40970-1 emergency cut-off switch.

What color is the MP40970-1 switch? The MP40970-1 emergency cut-off switch is white.

Is 722325 the same part as the MP40970-1? 722325 is the OEM cross-reference number for the Sierra MP40970-1, so it identifies the same emergency cut-off switch.

How much does the MP40970-1 weigh? The MP40970-1 emergency cut-off switch weighs 0.2 pounds.

What are the dimensions of the MP40970-1? The MP40970-1 measures 0.39 x 0.39 x 0.39 inches.

Is the MP40970-1 a genuine Sierra part? Yes, the MP40970-1 is a genuine Sierra emergency cut-off switch, not a generic substitute.

Where is the MP40970-1 made? The MP40970-1 emergency cut-off switch is manufactured in the United States.

Will the MP40970-1 fit any boat's kill switch circuit? The MP40970-1's 4-terminal design allows it to be wired into either a normally open or normally closed circuit, making it adaptable to different ignition wiring setups; no specific make or engine fitment is listed for it.