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KOEED

3 PCS Automotive Electromagnetic Power Relay MAH-112-C-4

3 PCS Automotive Electromagnetic Power Relay MAH-112-C-4

$18.55 USD
$18.55 USD $18.55 USD
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Automotive · Relays · MAH-112 Series · Electromagnetic · 3-Pack

What Is the MAH-112-C-4 Relay?

The MAH-112-C-4 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.

In short: Three electromagnetic power relays for heavy-duty switching — the kind you stock when you maintain a fleet and relay failures mean vehicles sitting idle.

How to Diagnose a Failing Relay Without Special Tools

Bench Test with a Battery and Multimeter

The 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.

Swap Test on the Vehicle

If 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.

Key Specifications

Part Number MAH-112-C-4
Type Electromagnetic power relay
Coil Voltage Verify from relay label (typically 12V or 24V DC)
Pin Count Verify from relay markings — check diagram on case
Quantity 3 pieces
Condition New

Contact rating (amperage), pinout diagram, and coil resistance — verify from the markings printed on the relay case.

Frequently Asked Questions

Why did all three of my relays fail at the same time?

Relays 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.

Can I use these relays for a non-automotive project?

Yes — 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.

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About Koeed Automation

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Important

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  • Within 3 days after placing the order, we will send you photos and videos of the product via email or WhatsApp for confirmation

International shipping - items may be subject to customs processing depending on the item's customs value.
Sellers declare the item's customs value and must comply with customs declaration laws.
As the buyer, you should be aware of possible:

  • Delays from customs inspection.
  • Import duties and taxes which buyers must pay.
  • Brokerage fees payable at the point of delivery.

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We ship to customers all over the world. Our primary logistics providers are DHL, UPS, TNT, FedEx, and EMS.

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All orders are processed within 72 hours of purchase. Please note that this applies to business days only.

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Shipping charges for your order will be calculated and displayed at checkout. Delivery estimates are within 7-14 days. Please note that these shipping times are only estimates and unfortunately, cannot be guaranteed.

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Damages

We take every reasonable precaution to ensure that products are not damaged. If the item is damaged in transit, please immediately contact us. We are not liable for any products damaged or lost during shipping. If you received your order damaged, please contact the shipment carrier to file a claim. Please save all packaging materials and damaged goods before filing a claim.

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Please verify you have the correct shipping address on your order PRIOR to making payment as this is the address we will ship to.

Return Policy

For more information, visit our Return Policy page.

International shipping - items may be subject to customs processing depending on the item's customs value.

Sellers declare the item's customs value and must comply with customs declaration laws.
As the buyer, you should be aware of possible:
• Delays from customs inspection.
• Import duties and taxes which buyers must pay.
• Brokerage fees payable at the point of delivery.

Contact Us

If you have any questions about your order, please contact us at moritta@koeed.com.

Return Policy

Return and Refund Policy

We want you to be completely satisfied with your purchase on our store. If for any reason you are not entirely satisfied, we're here to help!

Returns

You have a generous 30 calendar days to return an item from the date you received it. To be eligible for a return, ensure the item is in its original, unworn, and unused condition with tags and packaging intact. Retain your receipt or proof of purchase for eligibility. Please note that certain items are non-returnable like perishables, custom products, personal care goods, hazardous materials, flammable liquids, and gases. Reach out for clarifications on specific items.

Return Process

Commence the return process by reaching out to us at moritta@koeed.com. Upon approval, we will furnish you with a return shipping label and detailed instructions for dispatching your package. Unnotified returns will not be accepted.

Damages and Issues

Kindly review your order upon delivery. Notify us promptly if it arrives defective, damaged, or incorrect. We will address the matter swiftly.

Exchanges

Facilitate a swift exchange by returning the original item once approved and making a new purchase.

EU 14-Day Cooling Off Period

EU-bound shipments allow a 14-day cancellation or return period without justification. Conditions mirror standard returns.

Refunds

Upon receiving and inspecting your return, we’ll inform you of the refund status. Approved refunds are automatically processed within 10 business days via the initial payment method. Allow time for financial institutions to finalize the refund. For delays exceeding 15 business days post-approval, contact us at moritta@koeed.com.

Shipping

You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable. If you receive a refund, the cost of return shipping will be deducted from your refund.

Contact Us

If you have any questions on how to return your item to us, feel free to contact us at moritta@koeed.com.

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