How To Test and Diagnose Relays and Wiring [4 & 5 Pin]
ฝัง
- เผยแพร่เมื่อ 10 ก.พ. 2025
- Relays and wiring can be a real pain, and the whole process of testing and diagnosing can be daunting. If you simplify it and break it into pieces, it's not all that bad. We show you some simple ways to diagnose a relay and confirm whether it's alive or dead. You'll definitely want a multi-meter, some jumper wires, and a 12-volt source. Let's get started.
Kaiweets Multimeter: amzn.to/3xL0fG4
Alligator Clip Wires: amzn.to/3C7pvZI
High Amp Alligator Clip Wires: amzn.to/3R79Bmb
Keep current with our great content:
TH-cam: / shoptoolreviews
Instagram: / shoptoolreviews
TikTok: / shoptoolreviews
Facebook: / shoptoolreviews
Twitter: / shoptoolreviews
Finally someone who explains in detail how relays work and how to test them. Thanks a lot, appreciate it!
I'm glad I ran across your video. I tried watching other videos and reading how-tos. None of them made sense to me as they weren't explaining how the relay works. They were only showing how to test with whatever relay they had on hand. It didn't help at all. After your video, I can test my relays in seconds and now that's I know how they work I'll never forget this how.
My thoughts exactly! Have played with automotive electrical for decades and never understood relays. Not anymore.
Some one said, why he talks so much. If you really want to learn something. Then listen to the whole thing. Anyway I loved the video. Now I know how to check relays. Thank you so much for your time.
I saw that comment above. Some people will watch any video and then think of something negative to say about it (trolls). He talks more because he is explaining something in detail and that's all there is to it. I appreciate the details. Because this is a subject I am not very familiar with.
Ive been wrenching for 10yrs and been avoiding electrical testing. Time to take it head on as I'm doing lots of repairs as a side job for extra income. Once i master my diagnosis skills my price is going up!
Let's call it a 'consultation'.
Good basic information on how a relay works. Thanks for showing the Kaweets multimeter, it's the first time I'm seeing it. Look forward to more of your videos.
This was a great and simple explanation of how relays works and how to troubleshoot if the relay is good. Thanks. Keep it up.
Best relay testing video on the internet!❤ Thanks for sharing this.
Wow, thank you! That's why we do it. Thanks for watching.
You can even use a flat 9 volt battery and perform the tests. It worked for me. Excellent video man👍
Relays and solenoids are considered high current switches a lot of people are unaware of this. Yes the control side 85/86 is switched by the computer most times in an automotive application. Great video and I love that meter.
This video goes straight into favourites,
thanks Tim, and take care.
That’s great to hear. Thanks for watching
Thanks!
You bet! Glad we could help. Thanks for watching and thanks for gift.
Watch half a dozen of these, and yours is the one that worked for me. Thank you.
I didn't have a 12-volt battery so I used a 12v battery tender for power. It performed both tests perfectly without worrying about damaging the relays.
I been wanting to learn the process and this was an excellent video. Thanks!
This actually sense to me now. I still have questions and some confusion as to why a relay works for a short period then stops. However I now can begin going back through my system
The best and most complete explanation I've seen. Thank you.
Thanks. You explained the 87a which the other videos didn't make as clear. I ordered a repair manual. I hope the wiring diagrams are helpful. Getting prepped so when my starter doesn't turn over next time I can see if bypassing the relay will work and start to narrow down my problem.
I liked this video so much I watched it twice.
So glad i found this video. I finally understand how relays work. Thank you
I had a little understanding of relays, when I tried to add fog/driving lights on my '72 Toyota Corolla & a little background in electronics. However, I never completely understood what the numbers stood for & exactly which terminals did what, even though I successfully wired the lights. Now, as an old guy, you helped really understand. Thanks!!!
I'm in the exact same situation. Took electronic classes in HS and learned more in the army. Being in my late 50s, I am finally a pro with relays. Lol.
Great stuff man.. Thx!! I am sitting here at my desk with my fluke and power supply feeling like an absolute Genius thanks to you..
My only quibble is that it's not a resistor between 85 and 86, it's a coil that, when energized, creates the magnetic field to pull the relay switch to close the 87 and 30 contacts.
Some relays have a resistor across 85 and 86 to mitigate the destroying effects of a back EMF spike. Some relays even use diodes instead of resistors
This was really cool - I would love to see more about this. Specifically how you walk through a real problem when it's not some major component like a relay or a fuse.
I'm dealing with a fuel pump that's not working. Motorcycle sat for 8 years with fuel in the tank so I knew I needed to replace it. Since I was already in the tank, I replaced everything previously in the tank....the fuel pump, pressure regulator, fuel filter, float sending unit, all fuel hoses, wiring harness. Now the problem is when I turn on the ignition, the pump still doesn't sound. I added 2 gal of gas and still nothing. I even made a long hook so I could manually change the float sending unit and the level on the fuel gauge didn't change.
SO I'm thinking it's not getting any power to the pump. Fuses were fine - I checked the continuity and they're great. Changed both relays cuz they're old and cheap....still nothing. NOW I'm going to have to test the voltage at the relay and walk it forward but I don't know exactly how to do that. I'm also thinking I should check the plug on the outside of the tank that delivers power inside the tank. However I tried doing that but I'm honestly not sure if what I'm seeing is what it should be. It's confusing when you've never done this stuff.
This is just superb. Well explained nothing unnecessary and to the point. Thanks.
Diagnostic question maybe answered from this video. I had clicking lights in the interior and windshield wipers. They drained my battery. I am going to try this now! Thanks for the great video. Easy to understand
Great video. I was looking into buying a new multimeter and this new one with chargeable battery and the auto feature looks amazing and only being 40 something dollars on Amazon is a great buy. Thank you. I'm buying one now.
Thanks for sharing, it's helping get out of the rabbit hole.
Great video guys. I learned alot and got more understanding on the subject. Thanks Much
Super helpful ! Extraordinary detail !! I learned lots !!! Thanks mate !!!!
Thank you so much for the clear and easy tutorial.
Appreciate the video. This is what I struggle with at school. I understand it now.
Great video, I always knew what a relay did just didn’t know how it did it Thanks for talking in layman’s terms.
Excellent Video, great explanation of Relay functions. Love the test board and your Stainless Table to write on . Great Camera angle also 🙏God Bless You.
Sir, YOU make this video easy to watch. your teaching mannerisms are most helpful. thank you for breaking it down to my level. great stuff. I subbed based on this video.
Wow, professionally explained and quite informative 👏👏👏👏
Great video! Smart and thorough! 5 star rating and thumbs up!
Very nice presentation with model straight to the point an extremely easy to understand thank you so much.
Thank you. That was a very good demonstration of those types of relays.
thank you for your video it been a big help
Amazing video. 😊
Electrical on cars is simple. At least the basics are. 😊😂😊
thanks a lot...and the key is infrequently review and/or practice this application in order to retain it... peace
Great job letting us know about them explanation went a long ways
Thanks a lot
very good demonstration, made me understand, great guy!
Good Testing！ Very helpful for me
Can I just use a spare 12 volt mower battery with some alligator clip wires to energize the relay while testing? Do I risk damaging relay? GREAT video and explanation
Nice explanation. Thanks!
Very thorough! Thanks so much!
This was a great video. Thank you.
I’m wondering…can you then reverse and remove a component from this? If it’s a 5 prong feeding a faulty antitheft system preventing a vehicle from starting, can we eliminate the system and put a four prong to bypass?
Best video on relays I have seen yet. ❤l
Loved this video show something how easy it is to test relay before replacing in a wrong way
Love this explanation ❤️💯
Very clear
Great video my friend. Well put. Maybe some more specific examples as used in the switching process' in the car would really embed the learning. Knowing there is a high and low side is key, but how they interact in the different automotive situations ( indicators, pumps, etc ) exactly wouldbegreat, but maybe that video would be too long!
Super video, I'm ordering the crocodile clips!
This works sometimes: bang on relay. I had a horn relay that would not work. So I disconnected battery. Tugged, poked, whacked and shook relay. Would not come out. Read it had to be replaced with whole relay tray, or cut out. Hooked up battery to call it a night and presto it worked. I guess it was just stuck with a little corrosion. If does it again I'll drill 3 tiny holes in the top and spray silicone spray into relay to possibly fix corrosion issue for long time.
I'd say most ECU's would use grounds to control the relays, that's how all of the aftermarket ones i've used worked to control the fuel injection for instance because they aren't designed to have high amps passing through them.
Thenk you for the video is helpful God bless you.
100% clear explanation.
Best explanation ever . Thanks a lot
Great video!!👍
Awesome video! Amazing how such a simple thing doesnt have such easy to understand videos such as yours👍👍
Great video!!! Very informive!!
awesome video sir!
Go to test power across 85/86 and pop, smoke, awesome!!! Going to guess that's complete junk now. Thanks👍🏻
Hmm. I've got relays that don't have 87. It has 87A, but not 87. I'm figuring out that this relay is on all the time, but when the control side is activated, it turns off. It is a 4 pin relay.
The part # is FOOCLE FLS820-012-1B. There are absolutely zero that show up on a google search. The 1A & 1C show up, but not the 1B. Ironically, the others are 5 pin.
On the front of the relay, there is a white tag that says:
Red 12V DC
White Relay control
Yellow Pump A
Blue Pump B
I'm trying to use this relay to control a coil to a plug, for a Plasma spark ignition demonstration.
I'm using a 12V DC LED strobe light controller to energize the relay, to simulate breaker points to fire a spark plug.
This one is a head scratcher.
Great video on electrical relays
very Good information
Stumbled upon your channel. Very cool episode, learned something I’ve always wanted to know about. Thanks a bunch! Subscribed!!
Helpful, thanks for that vedio
Outstanding, well done!
AWESOME VIDEO!👍🏽🇺🇲 AND THE MOST HELPFUL IN EXCELLENT DETAILS! 👌🏽🇲🇽 YOU EVEN BOTHER TO GIVE US ADVICE AND LINKS ABOUT MULTIMETER THANKS A LOT MAN!
🇲🇽🤜🏽💥🤛🏼🇺🇲
Very thorough, Great video. What does it mean when the 87a across 30 open and giving numbers jumping up to 6.7? Does this mean that it’s a bad relay?
Between 85 & 86 you refer to it as a resistor. It’s actually an electromagnetic coil that pulls or releases the pivoting contact point, right? I’m sure has resistance, but it’s not a resistor in typical electronics terms. Great vid though!
See the answer I gave to @fix135 above. In addition to that, a coil is made of of loops of wire and wire has resistance, so technically it's also a resistor.
Excellent, excellent video.
Because of the way you explained how to test a 4 pin and5 pin
relay, I believe that I will be able to test a few relays on my
1999 GMC Sierra truck. I noticed that you used a 12 volt
battery with two short wires plugged into it. Where can I get
a battery and the two short wire pieces from? I see that I can get
the set of wire leads with the alligator ends attached from amazon.
Excellent video. You are a great teacher.
Glad it was helpful!
Thanks Buddy that's helped me a lot 👍
The markings between 85 and 86 is a coil (curvy lines) not a resistor (zig zag lines). The coil is an electro magnet. Otherwise great video. Love your channel!
There's also a resistor inserted across the coil to damper down the induced voltage created when the relay coil is switched on and off.
@@m101ist to help protect the ecm if the signal is used to activate the relay. I was used to it being a 12VDC signal when its wired for ignition switch activation. Now majority signals from the ecm
Yes,85-86 is a coil that pulls the load contacts to energize a fan motor or whatever but it goes to the device to put under load .
😊@@imfloridano5448
@@m101ist❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤ì❤i
Great video, informative on to work with relays.
thanks so much for valuable information my car can now start, it was showing all those symptoms
Great video. Thank you
Thank you sir for the help
You're very welcome. Glad we could help. Thanks for watching.
I GET IT !
B/C If your relay is good there might be a problem somewhere else !!!? THANK YOU !!
Nice! For us who enjoy mechanics but not so much electronic
thanks so much, that was valuable information
Excellent informative video thanks. Excellent info and great explanation!!! Thank you!.
Wow... Thank you! Amazing video
Thanks for de info 👍🏻grts from Belgium
Super helpful ! Thanks..
I have a 97 Camry fan 4 pin relay Bosch. Has no 87 but listed as 87a? It seems to be working when tested with a multi-meter and 12 volt source but my relay testers is saying its bad.
Man you break it down so well. Thank you.. okay but check this out I got high on PCP and took a hammer to my ignition fuct off everything my ignition signal sticks, basically smashed out everything from the steering wheel to the tilt lever. I'm left with a bare steering column a wiring harness for my ignition switch with one red wire in a cluster of wires what's a clip. Thankfully the clip is intact and I believe that's to my ignition switch. But I got to get the hell out of here so how do I start my car. I can send you a picture that's what I'm dealing with if it makes it easier for you to help me with s*** please help😮
Great video! May I get to know the model of your multimeter?
Great information 😊
Thank you
What about 87 & 87a "normally open & normally closed" like having an illuminated indicator lamp on when an accessory is in the off position?
That's how I understood the difference between 4 and 5 pin relays.
Pity the link to Amazon for the multi-meter says unavailable. A very good video explaining relays.
so useful!!
Nice vid!
Thank you very much.
VOLVO CENTRAL LOCKING DIAGNOSIS: SUPPOSE my relay is good and the fuse is good but the wiring between door switch and the relay is faulty? Do you have a video on the Plug that the relay plugs into? I need to know how to access the board behind my relays on my 30 year old Volvo. Thx, DDay, Maine
Great job 👍
Excellent informative video thanks
I am testing a 1733 5 prong relay. I measured the 85 tp 86 and it measured 74. In the video you said it should be 75 to 100. DOes that mean my relay is bad? My other test showed OL. I did not test with power since I did not have a power source handy. Thank you
Great video
😮🎉😮🎉😮🎉---😊,
WOW! Thank you so much for taking the time to make this video too inform me about the routes electricity takes when ground/12 volt / 85/87A/420/69 etc .. ..... .. .
My experiments haven't been as fulfilling as I know they were many moons ago. Installing these relay switches inside of the cranium of two species of saltwater fish. I could not get the wiring correct from the electrical brain diodes running to the tail then to the relay fuse and of course it grounded to a hollow bone in the jaw. Then wired to the fins, and from the fins to the 12 volt battery installed exterior of the scales. I couldn't tell you how many salmon I use for practice and I had very neat effects/ movements on command, forward left right and even reverse. It isn't a very good backup job reversing for the fish but it tries even though it doesn't know what it's doing. sounds out of the voice box ( fish don't have specialized vocal cords or larynx's so the most popular way is through a tribulation, the same way crickets makes sounds the fish rubs two phones together or clicks producing audible 112 decibels mimicking music or songs that are being played through underwater sonar speakers. And of course all the tones are in the range of the eardrum that the earthworm grows naturally.. But everybody knows that. (The unnatural eardrums have never worked going back to 19 63 when Klaus Schmidt revolutionized the hearing aid affects/quality for the endangered scouts that were trapped inside of the cave during the mining accident in Mexico. I digress
🤔 I lost my concentration where was I.....
Oh yeah! So I got the huge fish wired up with the relay on the interior of the cranium with the 12 volt battery that is securely placed on the dorsal fin. With no holes or anything drilled into the fish because the last thing I would want to hurt would be the beautiful beautiful experimental fish.
If anybody would be interested in the conclusion of the first round after this kind TH-camr gentleman taught us all about relays, I'm happy too provide my link to the science paper that is peer-reviewed by my peers at the institute.