{"product_id":"dc-12v-40a-spdt-automotive-relay-4-pin-car-alarm-high-load","title":"DC 12V 40A Automotive Relay SPDT 4-Pin | Car Alarm \u0026 Circuits","description":"\u003ch2\u003eDC 12V 40A SPDT Automotive Relay – 4-Pin High-Load Car Relay\u003c\/h2\u003e\n\u003cp\u003eKeep your vehicle's electrical systems running reliably with this heavy-duty \u003cstrong\u003eDC 12V 40A SPDT Automotive Relay\u003c\/strong\u003e. Built for high-load switching applications, this 4-pin (also available in 5-pin) relay is an ideal component for car alarm systems, lighting circuits, starter circuits, and a wide range of 12V automotive wiring projects. Its single-pole double-throw (SPDT) design provides one normally open (NO) and one normally closed (NC) contact, giving you flexible switching control in a compact, durable package.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHigh Current Rating:\u003c\/strong\u003e Handles up to 40 amps, making it suitable for high-load automotive circuits\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSPDT Configuration:\u003c\/strong\u003e 1 Normally Open (NO) + 1 Normally Closed (NC) contact for versatile switching\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e12V DC Coil Voltage:\u003c\/strong\u003e Designed specifically for standard 12V automotive electrical systems\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e4 or 5 Pin Options:\u003c\/strong\u003e Compatible with a variety of relay sockets and wiring harnesses\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDurable Construction:\u003c\/strong\u003e Sturdy plastic housing with metal contacts for long-lasting performance\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWide Application:\u003c\/strong\u003e Suitable for car alarms, horns, headlights, cooling fans, starters, and more\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLow Voltage Compliant:\u003c\/strong\u003e Rated for low-voltage use (below 50V AC or 75V DC) per EU LVD standards\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompact Black Design:\u003c\/strong\u003e Discreet, easy-to-mount black housing fits standard relay locations\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCoil Voltage\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eDC 12V\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCurrent Capacity\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e40A\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eContact Type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eSPDT (1 NO + 1 NC)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePin Configuration\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e4 or 5 Pins\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eConstruction\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003ePlastic housing, Metal contacts\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eColor\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eBlack\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eVoltage Standard\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eLow Voltage (Below 50V AC \/ 75V DC)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCountry of Origin\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eMade in China\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eWhat's in the Box\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e1 × DC 12V 40A SPDT Automotive Relay\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eRelated Products You May Like\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/10-pack-rubber-strain-relief-cord-boot-protector-sleeves-4-6-5-2-6mm\"\u003e10-Pack Rubber Strain Relief Cord Boot Protectors 4.6–6mm\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/waterproof-cable-gland-set-pg7-pg9-nylon-connectors-10-pack\"\u003e10-Pack Waterproof Cable Glands PG7 PG9 Nylon Connectors\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/25-in-1-precision-magnetic-screwdriver-set-pro-repair-tool-kit\"\u003e25-in-1 Precision Magnetic Screwdriver Set | Pro Repair Kit\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eLearn more: \u003ca href=\"https:\/\/www.fueleconomy.gov\/feg\/drive.shtml\" target=\"_blank\" rel=\"noopener\"\u003eFuelEconomy.gov driving efficiency guidance\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: What is an SPDT relay and how does it work in a car alarm system?\u003c\/h4\u003e\n\u003cp\u003eA: An SPDT (Single-Pole Double-Throw) relay has one common terminal and two switching contacts — Normally Open (NO) and Normally Closed (NC). In a car alarm system, the relay acts as an electrically controlled switch: when the alarm coil is energized with 12V DC, the common terminal switches from the NC contact to the NO contact, allowing you to trigger horns, sirens, or cut ignition circuits without running high-current wires through delicate alarm modules.\u003c\/p\u003e\n\u003ch4\u003eQ: Can this relay handle accessories like headlights, cooling fans, or horns?\u003c\/h4\u003e\n\u003cp\u003eA: Yes. With a 40-amp current capacity and a 12V DC coil rating, this relay is well-suited to switch high-draw automotive accessories including headlights, electric cooling fans, horns, and starter circuits. Always verify your accessory's peak current draw does not exceed 40A before installation.\u003c\/p\u003e\n\u003ch4\u003eQ: Is this relay compatible with standard relay sockets?\u003c\/h4\u003e\n\u003cp\u003eA: This relay features a 4-pin or 5-pin configuration that fits most standard automotive relay sockets and wiring harnesses available on the market. Check your socket's pin layout (typically labelled 85, 86, 87, 30, and optionally 87a) to confirm compatibility before installation.\u003c\/p\u003e\n\u003ch4\u003eQ: Does this relay require any special tools to install?\u003c\/h4\u003e\n\u003cp\u003eA: No special tools are required. The relay plugs directly into a compatible relay socket. For direct wiring, basic automotive wiring tools such as a wire stripper, crimper, and a screwdriver are sufficient. Always disconnect the vehicle battery before working on electrical circuits.\u003c\/p\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"What is an SPDT relay and how does it work in a car alarm system?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"An SPDT (Single-Pole Double-Throw) relay has one common terminal and two switching contacts — Normally Open (NO) and Normally Closed (NC). 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