





⚡ Upgrade your ride with relays that work as hard as you do!
The EPAuto 30/40 AMP Relay Harness 4-Pack delivers robust 40A switching capacity with ultra-fast 10ms operation, designed for automotive pros who demand reliability across extreme temperatures (-40°C to 125°C). Each set includes heavy-duty molded relay sockets with 5-wire harnesses, UL-listed for safety, making it the go-to choice for upgrading headlights, starters, and more. Trusted by thousands, these relays combine professional-grade durability with plug-and-play ease—don’t get left behind on your next vehicle upgrade.
| ASIN | B072QXDZRD |
| Best Sellers Rank | #20,936 in Automotive ( See Top 100 in Automotive ) #9 in Automotive Replacement Starter Relays |
| Brand | EPAuto |
| Brand Name | EPAuto |
| Coil Voltage | 12 Volts (DC) |
| Connector Type | Relay Socket |
| Contact Current Rating | 40 Amps |
| Contact Material | Silver |
| Contact Type | Spdt |
| Current Rating | 40 Amps |
| Customer Reviews | 4.7 out of 5 stars 6,850 Reviews |
| Manufacturer | EPAuto |
| Maximum Switching Current | 40 Amps |
| Minimum Switching Voltage | 1 Volts (DC) |
| Mounting Type | Socket Mount |
| Operating Time | 0.01 Seconds |
| Operation Mode | Automatic |
| Specification Met | UL |
| UPC | 707129801449 |
| Upper Temperature Rating | 125 Degrees Celsius |
| Wattage | 560 watts |
J**S
Work great for a variety of automotive things.
I have used these for everything from upgrading headlights to electric chokes and even as a starter relay on an 84 Chevy truck and had no issues. The relays are sealed well so you don't have to worry about water intrusion in the relay itself. The included wiring is a nice bonus, but it is NOT sealed so water can still get into the connections. Also the wires that are included maybe on the small side for any sustained high current, certainly not suited for a continuous 30 or more amp load. Luckily the terminals are easy to remove from the connector so heavier wire can be installed and still look professional. The mounting bracket is a bit flimsy but holds the relay in place. For the price you cant hardly go wrong, certainly much cheaper than buying them at a local parts store. Update 10/5/23 Been using these for several years now and only had one failure so the relays themselves are pretty good, specially for the price. Just remember the included wires are NOT up to the task of a 30 amp load, even if the relay is. The wires are marked as 16awg which is OK for up to a 15 amp load, depending on the length of the wire used in the circuit and how much voltage drop is allowable. Have successfully used for electric radiator cooling fans after replacing some of the wires in the relay connector. Personally, I make new wires for the power supply side and the load side of the relay (terminals 30, 87 [& 87a if it is being used]) if the load is over 10 amps. Terminals 85 & 86 are fine since they are just used to activate the relay and that does not use much current at all. As always, make sure any hot wires are fused with an appropriate sized fuse for the wires and circuit load as close to the battery as possible. Relays are still 5 star, specially for the price. The wiring and connector would be more like a 2 since it is so far below the rating of the relay, but again, for the price you can't expect much. At this price point, you are lucky to get a connector at all.
P**D
Never know when you'll need a couple of these....
Purchase them in volume. Work well with add on fog or driving lights. Or performing a bypass method for high and low beam when your million dollar daylight running light module expires. Two of these and a fuse holder and a little time and your in business. Great quality and work very well.
Z**L
Nice to have around for non-critical applications
I bought this set of relays so I could use one to run an electric fuel pump on my lawn tractor. The factory diaphragm fuel pump is tired and I didn't want to mess with it, so I bodged an electric pump with a relay to turn it on. I selected these because they came with the harness pigtail, they were relatively inexpensive, and the reviews were good. Those are my criteria when I buy non-critical parts to keep around. I don't want to spend the money on name-brand relays for non-critical applications such as this because an inexpensive relay will do the job just fine, and even if it doesn't, my lawn tractor is never more than 200 feet from my house. Would I use this relay on a critical system in my car, IE fuel pump? Only if I was in a real bind, and in that case I'd throw as many spares as I could find in the glovebox. Not saying these relays won't work (the one I installed is working quite well), but I have no idea what this company's QC is like or how good they will be in the long run. I suspect that most people who buy these will use them for non-critical applications-- accessories or lights on their car, adding a circuit, etc. For this they'll probably be fine, and if they're not, they'll be easy enough to swap out for something better. As for me, I'm glad I have them for little project like my lawn tractor. If I manage to use them all, I'll buy more.
A**R
Great quality
Great price fast delivery
W**R
Quiet handy for little projects
Relays seem to be well built, reliable, sturdy, and capable. Wiring harnesses also seem to be well built. Just an FYI, even though the relay is rated for 30A, doesn't mean you should run 30 amps through it. As others have mentioned, the wiring harness included, is not rated for that high level of current.You should always factor in, 'the weakest link', i.e. if the wires feeding the relay will not handle more than say 8 amps (and I don't know what these wires will handle), it doesn't matter much how strong the relay is, you don't run more than 8 amps through the wires.... duh. and even that is pushing it. When an overall circuit is rated for 8 amps max, you should not get anywhere near 8 amps anyway. Pushing anything to the max is never a good idea. Besides, running high current through a mechanical relay, the contacts will arc, carbon will build up on the contacts, the contacts will become pitted, and eventually.... one day, when it energizes, the contacts will stick, and whatever it is will be 'On' continuously... if it comes on at all. You might want to consider using a solid state relay (DC) or a triac (AC) imho. Any time you are dealing with any type of high current, get someone that has an electrical engineering degree or background to look at your circuit designs... just because you may know how-to, doesn't mean you know how to. One of my kids kept leaving their car lights on, apparently they have a lot on their minds these days. I used this to build a simple 'lights-on' circuit. This particular car doesn't have one. I found a line that goes to 12 volts when the key is turned on, and found the "Lights" wire. I wired it up, so if the lights are on, and the key is off, a Piezo Electric buzzer sounds. It is very low current, and works great. We haven't had another "accidentally left the lights on" incident since. These are quiet handy for any number of little projects you might have.
W**G
Fit 2007 Mercury Mariner with minor modifications
This is the third set I've purchased for a 2007 Mercury Mariner Hybrid. They seem to work perfectly. But the car has a problem. Periodically, the dashboard beeps and displays "Stop Safely Now," requiring that I come to a full stop, turn off the engine, pull the key out, wait one-half second and restart and get back on my way. I think, but am not sure that this problem is less frequent with new relays. These have 5 pins, while the OEM relays had 4 pins, but seem to work perfectly once they are modified as described next. And, after the modification, the job is simple--remove the cover to the fuse box on the driver's side near the firewall, unplug the old relays and plug in the new ones. On the outside of these relays, each has a metal spade bracket slipped into a female plastic "box." On a previous set, with a little effort, I pulled out the metal spade, but the female retaining "box" interfered with a shoulder on the fuse box next to each relay receptacle. Previously I shaved off the box with a box-cutter, knife or something like that. This time I used a handheld angle grinder with a cutting wheel to shave off this plastic retaining box, which removed the box and the metal spade at the same time in about 3 minutes. Then these fully seated into their receptacles. I'd buy these again, and have now done so twice.
A**A
Good relay
Replacement relay needed on a John deere backhoe. Fit as advertised. The advertisement online at Amazon gave an accurate description.
E**I
My husband loved them
My husband found them to be very good
Trustpilot
5 days ago
3 weeks ago