I know this video is like 8 yrs old, but I am so glad it is still up. Yesterday at the car show, a fan came up just after I pulled in and parked. He was sharp. He noticed right away one of my dual elect. radiator cooling fans was not working. It has a built 460 in the 67 Mustang and it has been running hot.(It is also very hot outside too). I planned on putting a toggle switch in anyway so I can turn them on earlier rather then when it is 185 deg or higher. Wired up the toggle switch, and test both relays for the click. Will finish up with the resistance check tomorrow. Thanks so much for sharing this info. It has helped so much. Cheers from Motown.

A couple basic tips for those who don't know: A normal switch has 2 basic states, normally open (NO) or normally closed (NC). When power is sent to a switch it change states, so a NO switch will become closed. That means power will be distributed to any legs designated after the switch. A NC switch does the opposite, when signal power goes to the switch it will open the circuits, terminating power distribution. Troubleshooting note: A digital multimeter had two fuses. One for checking voltage, and one for checking continuity. ALWAYS check voltage before checking for continuity. When checking for resistance the meter uses its own power to test the circuit. If there is voltage on the circuit it will automatically blow the fuse because you're checking resistance on a hot circuit. Check voltage before resistance and you'll never need to replace fuses or worry about testing a hot circuit

This is one of the most well laid out and simple to understand vids on relays. Thanks for not making it to complicated.

Best video on relays I have seen so far, simple, well explained and easy to follow for complete beginners like me. Well done!

Your explanation was simply the best one! I made me remember my school class about sensors and switches. Thank you so much for your video material.

Very good info for us who are "challenged" when it comes to electricalal tasks. Thank you.

Watched a couple of videos for testing relays and this was the most direct approach and easy to follow.Thanks.

WOW, thank you for putting together such a good lesson. Straight forward, and will really help me confirm if I need a replacement relay for my fan. You are doing good for the little people! Thanks again!

Great job keeping it simple. Other videos go to deep in all the functions of a multi meter. I'm new at this @ 63 years old and starting a new hobby. I am intelligent, but, just never tried learning about cars or electronics, as my career was in sales. Thanks fir talking to me simple, with integrity.

For all the questions about "Make sure the ground is connected to ground and the power goes to power," ... Typically- pin 85 is ground (negative) pin 86 is power (positive) pin 30 is constant supply power to whatever is being activated by the relay pin 87 is the output of pin 30 when it gets switched on. 30-->87 To be certain which pin (85 or 86) is positive or negative...the diagrams often have a symbol of a diode (triangle and a line) on either pin 85 or 86, whichever pin the "line" side of the diode symbol goes to is negative. Connecting power backwards will simply do nothing, this is what the diode does.

Just what i was looking for. A well explained procedure on how to test a relay the right way. Thanks very much for posting.

You are very helpful to us learning about relays!!! Keep up the GOOD WORK!!

I have been watching DIY car repair videos on You Tube for awhile and you have some of the easiest, most useful, and simply best videos out there thanks.

You are by far the best teacher on youtube when it comes to cars!! Very insightful and easy to understand. Thank you so much ratchets and wrenches love your work!!!

Excellent video. You have a natural talent for instructing people about technical things. This really helps me.

The flapper is called a contact. Thank you for the videos! Love your channel ❤️

Outstanding video! I am working on a RAT PASSAT, and I think now I can finally test relays, THANK YOU!

great video man, short simple and to the point

That "flipper" is actually magnetically activated, and the contact looks like the points in old cars, but on a 5 prong resistor, the point is double sided. You video is really good, it helped me tremendously.

Good video on continuing to verify that that flapper, normally opened: bridge,switch,etc. has the continued loop for that circuit.👍

Thanks for the video, it helped me diagnose and fix the power windows on my 89 Benz. Bad relay! Thanks again!

Thank you for that video. I contacted three auto parts stores in Atlanta each told me that a Starter Relay cannot be tested. I will try this method Thank you.

Thanks bro...you just fixed my Polaris Diesel. I've been hunting the issue for days and days!

This guy is great! Thank you for explaining how to test a relay in simple terms and clarifying why the resistance is important .

really good presentation of how to get power for bench testing. and explaining the diff between good and bad parts i have seen the half hazard testing. kudos

I appreciate this. I'm having to hunt down individual components for an appliance controller board that has multiple relays. Watching circuit board videos, they just touch contacts and don't explain why. This makes it more understandable and by your explanation, theirs are incorrect. I am extremely grateful for this! Now to figure out how to run a current through without desoldering the individual relays. 🤔 Can't clip onto anything... I'll probably need a spare pair of hands. Thanks again. You're a gem.

Thanks for this video! My rear defroster in my 2003 Acura TL wasn't working. Power light for it would come on but no power was going to the defrost grid on the window. I removed and checked the relay with a 12V power source and it clicked, but no reading on the other leads. Just ordered a new relay and hopefully the new one solves the problem. Thanks again!

Ratchets and wrenches, love your videos. I just wanted to add one thing you forgot to mention. 95 percent of the time a resistance or continuity check is perfectly fine but sometimes a bad switch will show good resistance but as soon as you load it with more current than what the multimeter can put out it will go back to an open circuit. This concept burned me a couple times before I understood it and will make you go crazy if you aren’t aware.

Thank you . I have a CEN-TEC relay tester tool that does both the switching test and the continuity test at once BUT until I saw your video I didn't fully understand it was doing that. Just toggling mode 1 and mode 2 on tool and matching readout to answer in booklet. So I am like a kid with a calculator that didn't learn to add. Thanks for teaching .

SO FAR THIS VIDEO IS THE BEST TO UNDERSTAND CLEARLY VERY SPECIFIC AND SIMPLE, THANKS, NO WAY NO GET CONFUSED, OTHER VIDEOS GOT ME FRUSTRATED I KNOW SOME GUYS MEAN WELL, BUT THIS ONE VIDEO IS RIGHT THERE

In like the way you explain things. Obviously, you got stuck on the word "Switch", but watching this and your other videos, its very clear (despite that one small hang up that occasionally happens to us all) you really know auto-mechanics. Thanks and keep 'em coming.

You have no Idea how much your knowledge helped me, thanks for a very thorough explanation. Have a great day!

Thanks to you, I found my problem so much quicker. Relay was clicking, but no resistance. Much appreciated.

You are the man! Thank you so very much for this video. I have two after market relays in my Porsche 930 that i have checked about 10 times with the click test.....Both are actually stuffed! Fingers crossed she will start in the morn!

Fantastic video. Your explaination is very clear and the best I've seen for checking a relay.

Great vid man, going to check the fan relay in my work van tomorrow. Thanks for the tips in here bro!

Straight to the GD point. Clear and concise. Thank you very much bro!

Excellent! Very easy to follow and now I can test my relays. Thank you!

Great video, thanks for this. I have a intermittently working relay, would that show resistance? Or is there another test we can do? Assuming it stops working when under load for a long time. Fuel pump relay on a MY2000 Nissan 200sx.

Very smart sir... Keep making good videos I can actually say I've learned something new I usually just tested for the clicking sound and never thought about doing the test your way I will have to try this tomorrow...

Great job! Thank you! I like the delivery and straight to the point approach!

Thank you this was very informant and explained beautifully and simply. Keep up the great videos!

Check The OHMs on the 2nd relay without power being connected between 85 and 86, Then you will get the connection of 30 to 87 that you had on the first relay. Relays can be (NO) normally open 1st relay tested OR (NC) normally closed 2nd relay tested. Had you checked both relays with power applied and without power applied you would have found both relays to be good. Just that one completed a circuit and the other opened a circuit. Relays can also be (Single Pole Single Throw)(Single Pole Double Throw) (Double Pole Single Throw)(Double Pole Double Throw) That is the reason most relays have the diagram on them so you know which one you are working with. Had you looked at the diagram closely on your relays you would clearly see that the first shows to be closed between 30 and 87 and on the 2nd to be open between 30 and 87 meaning when energized 1st relay connects 30 to 87 and the 2nd disconnects 30 to 87 . Note when replacing any relay not only do you need to how it works to say it is bad, you need to make sure the replacement operates the same way. Or you can create a bigger problem than the one you where trying to fix. Thanks for the video it is done very well and is informative and a great way to test relays. Just make sure and test your relay with power and without power as you did on the 1st if it switches from on to off or vise verse chances are the relay is good..

Great video! An excellent and simple explanation and description of how to test a relat and how a relay works.

Wow. I just tested a relay on my Nissan Frontier. Got the relay to click but when checking with the multimeter I got nothing. Would not have done that second check without this video. Thank you.

Thanks for the great explanation. Has helped me loads with fault finding 🖒

Very helpful video! Thank you! I used the info to test and find a bad relay in my starter circuit. Good job.

The “flapper” is a switch. I’m studying to become an electrical engineer, and I’m having car issues which brought me here. You have a really good intuitive understanding of electrical circuits. You should buy a breadboard and dive in a little deeper!!

G'Day from DownUnder Sydney Australia I love what u did, every little bit helps thank u matey, have a great day :)

I feel confident after seeing your video that I can test relays THANK YOU!!!!

The flapper is a switch...one of the few things I learned in college. I love the footprint on the floor.

haha np, glad the video was helpful to you. Cheers

Extremely well done. Clear and concise and removing all assumptions.

Looks like I came late to the party, but great vid .. well explained. As to the "flapper" you can call it a "switch", which is all that any relay is. As to the second test, most people forget that mutimeters are protected against significant voltages and IF that circuit was being completed, the meter would have read a resistance of zero, or close to it (all wires, even those used to supply electricity to our homes, have a little resistance, though it may be below the capacity of the meter to even measure). Final point, the symbol, Ω, is the Greek letter "Omega" .. sounds like "ohm-A-ga" (not proper phonetics, but illustrates the connection :) ). Love your videos, and have been recently applying them to a car that cranks but won't start .. major pain!

It has been a very long time sence I have tested a relay. This video has been helpful.

THx, actually gave me a good ABC to on how to approach relay's Cheers from Denmark.

Good video... another good way to start the test is to see if you have initial resistance across the switch gate, you should have resistance when it's not powered. If you don't then you know without even powering it that it's bad.

Very nice, clear, clean and correct. Great job, thnx for taking the time to do this.

Never mind. I saw your other video on how to test for 3 pin relay. Thanks for the great vids.

Awesome bro, very clear and to the point. Oh and we usually call the "thing that closes and opens a series an "arm". Not sure thats the right terminology, but thats what we call it. Anyways, great video.

An excellent video. You have explained this very clearly. Many thanks.

Great video. Thanks for the help.

I really liked the fact that resistance is discussed here, it seems to be often over looked in the diagnosis... I would prefer to test it while running to see if it differs under a load that the car provides...

Sometimes the very simple explanations are best. Great job!

Clearly describes the process of correctly testing a relay. As shown, one can't rely on just the sound of the relay "closing", supposedly completing the circuit. Educational video, well done.

Rather than look for a certain resistance I set my multimeter to continuity across terminals 30 and 87when energising 85 and 86. Appreciate the video!

Excellent work, very helpful. Thank you!

Thank you for teaching me this test!! Best relay test video in the world.

You might have just saved me these days of looking for a problem that is not there. THANKS!

THANK YOU for explaining so well..... Subbed and going to keep watching more !!!

Thanks for putting it in layman's terms so I could finally get it!

Just found a bad relay, thanks for your video. Much appreciated. Working on my 89 s13 hatch with aem standalone. With the relay plugged in, I get battery voltage to all my grounds even at the ecu pins. When I disconnect my cam sensor and grounds i have injector voltage. Obviously when they're plugged in, one or both at the same time, I have no voltage at the plug to my injectors. Going through my wiring a million times and determining I have everything pinned properly, I couldn't figure out what was happening. Testing this relay, and concluding it's bad, will hopefully fix my issue. The relay clicks when connected to power and ground, but shows 900 ohms when testing. So given your video, it's to my understanding that it's bad. I'll replace it and hopefully it does the trick. Thanks again.

That's the same relay for my 2007 BMW 328i Fan 👍thanks you saved me alot of time and taught me something!

The video had a air of being educational . Thank you , I enjoyed it .

great vid very easy to understand .have you any idea why the central locking on my passenger and drivers door wont work,checked the relay as you explained in your video and the relay seems fine,

Thanks for your comment, GL.

Awesome job of explaining how to test a relay and driving home the point to check the resistance across the circuit!

thank you for this, it helped me out so much now I know how to test a relay so to take it out of the equation while trouble shooting cheers!!!

This is hands down the best video!

That's the best video for checking relay. So complete Gracias

Very useful tutorial, many thanks for posting.I'm going to get my multi meter out and find out why my LH headlamp isn't working!

Awesome and clear video - thank you for making it!

Great videos.Where on the Nissan Patrol 2006, 4.5 can I look for the fuel pump relay?

The most helpful information about testing relay.

Hermano Great video on testing the relays,finally somebody help me understand,gracias colega.✌🏾️

Well done , much appreciated , " double check " that's going to echo in my head , thanks to your efforts .

This is the first video i ever subscibed on utube very helpful

The first video that goes from A to Z. Thanks! By the way, when energized, is there any voltage between 30 and 87?

Perfect video, No hidden things Thanks brother.

Can a bad relay cause an accessory to not shut off? Pressingly the heater fan in My Rubicon, everything works as it should, however when I switch the fan control switch to the "O" position, I'm still getting low fan out of the vents,

Ratchets And Wrenches thank you for this video

I thought this was very helpful. Explained in a simple understandable way

I saw another video and it said to make sure there is continuity between the two connections. Is continuity enough or do i need to check resistance also?

VERY EXCELLENT IN YOUR FACE - DIAGNOSTICS ....VIDEOS YOU PRODUCE .... VERY CLEAR , VERY VERY EDUCATIONAL .... GREAT JOB MAN!!!!!!

thanks for the video. I have cooling fan issues. I live in southern Missouri and have no a/c so I need both fans running. (98 Celica gt)

so helpful, thank you :); is it possible to just check using the voltmeter without having that extra battery connected?

Fantastic explanation and video!! Thank you very much!!

Great Video . . . Thank you, for taking the guess work out of testing.. Pls keep them great vids coming . . .Way to Go :)

This helped me so much thank you for the great video!

Thank you very much, I found the problem, and you made it easy to understand!