{"product_id":"3-pcs-automotive-electromagnetic-power-relay-mah-112-c-4","title":"3 PCS Automotive Electromagnetic Power Relay MAH-112-C-4","description":"\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#0056B3;font-size:14px;line-height:22px;letter-spacing:1px;text-transform:uppercase;margin:0 0 24px 0;\"\u003eAutomotive · Relays · MAH-112 Series · Electromagnetic · 3-Pack\u003c\/p\u003e\n\n\u003ch2 style=\"font-family:Arial,Helvetica,sans-serif;color:#111111;font-size:22px;line-height:30px;margin:32px 0 16px 0;\"\u003eWhat Is the MAH-112-C-4 Relay?\u003c\/h2\u003e\n\n\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#333333;font-size:16px;line-height:26px;margin:0 0 16px 0;\"\u003eThe \u003cstrong\u003eMAH-112-C-4\u003c\/strong\u003e is an electromagnetic power relay commonly found in automotive fuse boxes, industrial vehicle electrical panels, and engine bay relay banks. The \"MAH\" prefix identifies the manufacturer series, \"112\" is the base part number, and \"C-4\" likely denotes the contact configuration and mounting style. This listing is for a 3-piece set — ideal for fleet maintenance, race car harness building, or keeping spares on the shelf for troubleshooting.\u003c\/p\u003e\n\n\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#333333;font-size:16px;line-height:26px;margin:0 0 16px 0;\"\u003e\u003cstrong\u003eIn short:\u003c\/strong\u003e Three electromagnetic power relays for heavy-duty switching — the kind you stock when you maintain a fleet and relay failures mean vehicles sitting idle.\u003c\/p\u003e\n\n\u003ch2 style=\"font-family:Arial,Helvetica,sans-serif;color:#111111;font-size:22px;line-height:30px;margin:32px 0 16px 0;\"\u003eHow to Diagnose a Failing Relay Without Special Tools\u003c\/h2\u003e\n\n\u003ch3 style=\"font-family:Arial,Helvetica,sans-serif;color:#111111;font-size:18px;line-height:26px;margin:24px 0 8px 0;\"\u003eBench Test with a Battery and Multimeter\u003c\/h3\u003e\n\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#333333;font-size:15px;line-height:24px;margin:0 0 16px 0;\"\u003eThe fastest way to verify a relay: apply the correct coil voltage and listen for a click. Then use a multimeter in continuity mode across the contact terminals — it should read near zero ohms when energized and open circuit when de-energized. If the contacts show more than about 0.5 ohms when closed, they are pitted or corroded and the relay should be replaced. A relay that clicks but shows high contact resistance is failing — it will cause voltage drop and overheating at the load.\u003c\/p\u003e\n\n\u003ch3 style=\"font-family:Arial,Helvetica,sans-serif;color:#111111;font-size:18px;line-height:26px;margin:24px 0 8px 0;\"\u003eSwap Test on the Vehicle\u003c\/h3\u003e\n\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#333333;font-size:15px;line-height:24px;margin:0 0 16px 0;\"\u003eIf your vehicle has multiple identical relays (common in fuse boxes — fan relay, horn relay, fuel pump relay are often the same part number), swap the suspect relay with a known-good one from a non-critical circuit. If the problem moves with the relay, the relay is bad. If the problem stays with the original circuit, the issue is wiring, the load, or the control signal — not the relay.\u003c\/p\u003e\n\n\u003ch2 style=\"font-family:Arial,Helvetica,sans-serif;color:#111111;font-size:22px;line-height:30px;margin:32px 0 16px 0;\"\u003eKey Specifications\u003c\/h2\u003e\n\n\u003ctable style=\"width:100%;border-collapse:collapse;border:1px solid #eeeeee;font-family:Arial,Helvetica,sans-serif;font-size:14px;\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"width:40%;background-color:#f4fcfc;padding:12px 16px;border:1px solid #eeeeee;color:#111111;font-weight:bold;\"\u003ePart Number\u003c\/td\u003e\n      \u003ctd style=\"background-color:#f4fcfc;padding:12px 16px;border:1px solid #eeeeee;color:#333333;\"\u003eMAH-112-C-4\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"width:40%;background-color:#fafafa;padding:12px 16px;border:1px solid #eeeeee;color:#111111;font-weight:bold;\"\u003eType\u003c\/td\u003e\n      \u003ctd style=\"background-color:#fafafa;padding:12px 16px;border:1px solid #eeeeee;color:#333333;\"\u003eElectromagnetic power relay\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"width:40%;background-color:#f4fcfc;padding:12px 16px;border:1px solid #eeeeee;color:#111111;font-weight:bold;\"\u003eCoil Voltage\u003c\/td\u003e\n      \u003ctd style=\"background-color:#f4fcfc;padding:12px 16px;border:1px solid #eeeeee;color:#333333;\"\u003eVerify from relay label (typically 12V or 24V DC)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"width:40%;background-color:#fafafa;padding:12px 16px;border:1px solid #eeeeee;color:#111111;font-weight:bold;\"\u003ePin Count\u003c\/td\u003e\n      \u003ctd style=\"background-color:#fafafa;padding:12px 16px;border:1px solid #eeeeee;color:#333333;\"\u003eVerify from relay markings — check diagram on case\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"width:40%;background-color:#f4fcfc;padding:12px 16px;border:1px solid #eeeeee;color:#111111;font-weight:bold;\"\u003eQuantity\u003c\/td\u003e\n      \u003ctd style=\"background-color:#f4fcfc;padding:12px 16px;border:1px solid #eeeeee;color:#333333;\"\u003e3 pieces\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"width:40%;background-color:#fafafa;padding:12px 16px;border:1px solid #eeeeee;color:#111111;font-weight:bold;\"\u003eCondition\u003c\/td\u003e\n      \u003ctd style=\"background-color:#fafafa;padding:12px 16px;border:1px solid #eeeeee;color:#333333;\"\u003eNew\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#555555;font-size:13px;line-height:20px;margin:8px 0 24px 0;\"\u003e\u003cem\u003eContact rating (amperage), pinout diagram, and coil resistance — verify from the markings printed on the relay case.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2 style=\"font-family:Arial,Helvetica,sans-serif;color:#111111;font-size:22px;line-height:30px;margin:32px 0 16px 0;\"\u003eFrequently Asked Questions\u003c\/h2\u003e\n\n\u003ch3 style=\"font-family:Arial,Helvetica,sans-serif;color:#111111;font-size:17px;line-height:26px;margin:24px 0 8px 0;\"\u003eWhy did all three of my relays fail at the same time?\u003c\/h3\u003e\n\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#333333;font-size:15px;line-height:24px;margin:0 0 16px 0;\"\u003eRelays rarely fail simultaneously from natural causes. If multiple relays failed at once, look for a common cause: voltage spike on the vehicle electrical system (faulty alternator regulator, jump-start with reversed polarity, or a lightning strike on equipment parked outdoors), water ingress into the fuse box (blocked drain holes, pressure washing), or a short-circuited load that welded all relay contacts in that circuit simultaneously. Replace the relays but also find and fix the root cause.\u003c\/p\u003e\n\n\u003ch3 style=\"font-family:Arial,Helvetica,sans-serif;color:#111111;font-size:17px;line-height:26px;margin:24px 0 8px 0;\"\u003eCan I use these relays for a non-automotive project?\u003c\/h3\u003e\n\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#333333;font-size:15px;line-height:24px;margin:0 0 16px 0;\"\u003eYes — relays are agnostic to the application as long as the coil voltage and contact rating are within spec. These are commonly repurposed for home automation (Arduino\/Raspberry Pi controlling mains-powered devices through a relay), DIY CNC coolant pump control, greenhouse irrigation solenoid switching, and hobbyist projects. Just add a flyback diode across the coil if driving from a transistor or microcontroller pin.\u003c\/p\u003e\n\n\u003cdiv style=\"background-color:#16c8c8;padding:24px 32px;margin:32px 0;text-align:center;font-family:Arial,Helvetica,sans-serif;border-radius:4px;\"\u003e\n  \u003ch3 style=\"margin:0 0 12px 0;color:#ffffff;font-size:20px;line-height:28px;\"\u003eStocking up on relays?\u003c\/h3\u003e\n  \u003cp style=\"margin:0 0 16px 0;color:#ffffff;font-size:15px;line-height:22px;\"\u003eSend your BOM to \u003cstrong\u003eMoritta@KOEED.COM\u003c\/strong\u003e — availability and pricing within 24 hours, worldwide shipping.\u003c\/p\u003e\n  \u003ca href=\"mailto:Moritta@KOEED.COM?subject=RFQ%20%E2%80%94%20MAH-112-C-4%20Relay%203PCS\" style=\"display:inline-block;background-color:#ffffff;color:#0056B3;padding:12px 24px;text-decoration:none;font-weight:bold;border-radius:4px;font-size:15px;\"\u003eRequest a Quote →\u003c\/a\u003e\n\u003c\/div\u003e\n\n\u003cdiv style=\"border:1px solid #0056B3;padding:16px 24px;margin:16px 0;text-align:left;font-family:Arial,Helvetica,sans-serif;border-radius:4px;\"\u003e\n  \u003cp style=\"margin:0 0 8px 0;color:#111111;font-size:15px;line-height:22px;\"\u003eLooking for relay sockets, fuse blocks, or wiring accessories?\u003c\/p\u003e\n  \u003ca href=\"https:\/\/koeed.com\/collections\" style=\"display:inline-block;color:#0056B3;padding:6px 18px;text-decoration:none;font-weight:bold;border:1px solid #0056B3;border-radius:4px;font-size:14px;\"\u003eBrowse Products →\u003c\/a\u003e\n\u003c\/div\u003e\n\n\u003cdiv style=\"border:1px solid #eeeeee;background-color:#f4fcfc;padding:16px 24px;margin:16px 0;font-family:Arial,Helvetica,sans-serif;border-radius:4px;\"\u003e\n  \u003cp style=\"margin:0 0 4px 0;color:#111111;font-size:15px;font-weight:bold;\"\u003e\u0026gt; Diagnosing electrical faults on your equipment?\u003c\/p\u003e\n  \u003cp style=\"margin:0 0 8px 0;color:#333333;font-size:14px;\"\u003eTry the KOEED AI Diagnostic Tool for troubleshooting assistance.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/koeed.com\/pages\/ai-tool\" style=\"color:#0056B3;text-decoration:underline;font-weight:bold;font-size:14px;\"\u003eOpen AI Diagnostic Tool\u003c\/a\u003e\n\u003c\/div\u003e\n\n\u003cp style=\"font-family:Arial,Helvetica,sans-serif;color:#555555;font-size:13px;line-height:20px;margin:24px 0 8px 0;\"\u003e\u003cem\u003ekoeed.com — Your Trusted PLC Supplier. Industrial electronics, automation components, and specialty parts. Worldwide shipping with 24-hour quote turnaround at Moritta@KOEED.COM.\u003c\/em\u003e\u003c\/p\u003e","brand":"KOEED","offers":[{"title":"Default Title","offer_id":46117912314041,"sku":"317813397862","price":18.55,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0268\/8476\/7929\/files\/1_9c11ad9c-38c9-4e08-85e3-03c7a9f3735f.webp?v=1783336521","url":"https:\/\/koeed.com\/ko\/products\/3-pcs-automotive-electromagnetic-power-relay-mah-112-c-4","provider":"KOEED","version":"1.0","type":"link"}