How to Test a 3, 4 or 5 Pin Relay - With or Without a Diagram

[@bradical8198]

9 years later and this is still the best explanation on youtube

[@speway]

Incredibly detailed tutorial. Absolute love it! The only thing I would add is a brief description on what constitutes a ground. Thanks for your positive contribution to the KZbin community.

[@DavidLorellHoskins]

This was an incredibly helpful video. Your diagrams, explanations, and the stability/positioning of the camera all made this so simple to understand. Thank you

[@TurboJohn74]

I went to tech school for everything a/c, d/c and digital... but fifteen years later not using that knowledge had me lost helping my father with his truck. Your video was very easy to follow, and lit up the ol' brain again. Thank you so much!

[@kellypeterson3660]

Fixed my mercedes using this video. Had 74 ohms on 85 and 86. Relays opened and closed just fine. When 85 and 86 were powered and circuit closed, 30 and 87 had erratic ohms from .05 to 34.00. Tested 5 relays and that was the only relay with that problem. Replaced and now cooling fan comes on. Great video.

[@anthonylavallee4362]

Beats all the other confusing videos and written explanations. A big thank you is in order!!

[@sammacnab3514]

I really like this guy ! I was having problems with my ac compressor. I followed his instructions and found the AC clutch relay was bad. Thanks so much for posting this ! You're a great teacher !

[@Hoboappalachia]

This is the best video on relays and testing I have found on KZbin so far. Thank you! Keep it up.

[@Damienjking]

Another great video and an outstanding explanation. I would offer just one small word of constructive criticism for future consideration and I hope you receive this in the helpful way its intended. On the paper you layout the pin configuration and the wiring diagram which is very helpful to aid understanding. The one improvement I would recommend would be to make the wiring diagram match the actual pin layout. In other words, both the pin layout and the wiring diagram would have the pin numbers located in exactly the same place. This would make it easier for viewers with little electrical experience. I think this may be why a few people didn't follow what you were saying. Even with that small area for improvement, this is an excellent and thorough video. Thanks for your efforts.

[@willb5240]

Thank you! Out of the many videos on testing relays, yours is the only one I could find for those of us who have a relay that has no diagram or numbers at all. Much appreciated.

[@hubertwilliams6509]

I just have to say this.. You are a huge inspiration .. You gave me so much confidence and knowledge.. My 2003 Expedition started with a check charging system late February since then .. I've install new alternator, alternator wiring harness, 2 idle pulleys, removed and cleaned tension pulley, checked all my fuses and relays installed new engine belt ..today I got my truck running again and the reason why it did not start was one of the cables going to the fuse box was disconneted

[@TheMessiah91]

2024 the best and complete video on testing relays. Thanks man!

[@actualsurfer]

We are not yet completely sure...there is one more test, With the 85/86 energized and 87 confirmed "hot", you now need to put that test light back on 87a to see if it is also "hot". Because of your tutorial, thank you, I was able to diagnose my relay as bad. In my case BOTH the 87 and 87a are hot with the relay engaged. Causing all kinds of problems for my motorcycle. I tested it as Good but always traced the problem back to the relay. Did some more playing around with it and discovered my issue. Thank you very much for taking the time to make this video.

[@grosbeakmc]

Thank you for this easy to follow instructional video. I used it to test a relay - something I have never done before - and I found it failed the 4th step (the grounded test light did not come on when the relay was energized and powered). Great job!

[@passingasgarage2375]

Soooo, I have a Lotus Esprit V8 and was having some CEL codes and am trying to get to the root of the issue. I had a host of CEL codes related to the Heater circuit on the O2 sensors. I just replaced all 4 O2 sensors, as there are reasonable in price and easy enough to get at. The codes reappeared and so I thought.....after looking at the Fuses and Relays there was a relay for the O2 heater circuit. I pulled the relay and started to order a few relays.....and said let's check it out on KZbin and here I am. Your video made sense and was informative and I tested the relay that it worked, and that the resistance was good........sure enough clicking away strongly and the resistance was about 76.4, so within your prescribed range. I might have to test a cold start on the relay plug in and see if pin 30 is getting power at start. I would think it should when cold to heat up the O2 sensor. Thanks Again

[@joeh2253]

I just saw this video and it's fantastic. I've watched many testing of relay videos on You Tube and this is the best. I have a 5 pin relay that i needed to test and i didn't know what i was doing, now, i feel comfortable that i will get the correct readings. I will now be able to go to the next stip in getting my John Deere Gator working.

[@lakaidude99]

This is a great video. I'm pretty handy with a multimeter, however I've never been able to figure out testing relays. He makes it perfectly clear with full explanations for each step. I used a 12v jump box, my multimeter, spare wire/connectors, and made a phone charger adaptor that usually goes into a 12v cigarette lighter port in a car work as my tester (it has a small red light on it so I could tell that it worked). All in all it took less than 10 minutes to watch, setup, and go step by step to confirm that my 5 point fuel pump relay is in working order. 2 thumbs up, great video!

[@Dragon-Slay3r]

Lol

[@highlandminger4009]

This may be an old upload , but the section on diagnosing a relay w/o diagram stopped me from buying a fuel pump relay I didn't need...so thank you.

[@joecain88]

Hands down best explanation I've seen anywhere

[@rent2ownnz]

Thanks man.... been a long time since I diagnosed auto electrics a bit rusty. told me exactly what my brain had forgotten in 2 mins flat! good stuff.... Fixed my wiring issue and all running again, but had to eliminate 4 relays to move forward! cheers again!

[@KevinIndreland]

You're a genius....your videos are always a big help and you spell everything out for us. Thanks a million!

[@brians4377]

Excellent job! Thank goodness for KZbin and those that take the time to help others. You saved me a big headache and cash. Thank you!

[@erichlg]

Thanks for taking the time to make this video. It's 9pm and I am trying to cure an intermittent crank but no start. I now have confidence the relays are not my problem. On to the next step......

[@myRatchets]

Erich Greer Nice, glad to hear it helped you out. Hope you figure out the problem. Come to think of it I might do a video on Crank no start situations.

[@joeandgod1]

I agree with spelunkerd, that's the best,easiest, most understandable explanation on diagnosing relays on youtube.

[@myRatchets]

joeandgod1 thank you sir for your comment and watching.

[@tobydufrene1880]

Im having trouble with my 2018 jeep Cherokee. Your video will definitely help me when checking the relays. thanks for sharing the knowledge👍

[@ericb5447]

What a great teaching video. Thanks for putting in the time on making this for us to learn.

[@dentonscott6967]

You are an excellent Teacher. I am glad I found your channel. Your information is gold!!!

[@geomod6850]

Thank you. These videos are priceless in helping us keep our old vehicles on the road in these difficult times. Much appreciated sir. Good on you.

[@papatorr3669]

Just want you to know that you are a God send, Thank you so much. Your channel is my favorite in the DIY Car category. You've helped my son as well who is in the Air Force and is keeping an 88 Dodge Shelby Daytona on the road. I bought a fixer upper 96 Camry 2200 which started right up, but now cranks no start. Simple, thorough, humble, professional, educational, useful, effective...OK I'll stop. Keep up the good work. More technical is more better ; ) ! May not get as many hits, but the ones that do appreciate it more. Harbor Freight free meter?

[@vector226]

I've watched a lot of your videos and have to say, they are the best and most detailed videos I've seen. I feel confident to tackle the job after learning from you. Thanks for your hard work to get these videos out to people who want to learn how to do it themselves.

[@Angeldenis1987]

I was just watching to learn about relays. I don't need to check any right now, but now I wanna kust go grab a relay from my car and practice. :) . Nice Video.

[@WV591]

one of the 3 best auto repair channels on tube. i call it Auto TU

[@mbryant107]

This is an amazing video! I had NO IDEA exactly what relays did, what made them good or bad. It was just something you replaced and hoped you got it right! Thank you so much for drawing this out CRYSTAL CLEAR for me! This is amazing!

[@tamerasj]

I absolutely love and appreciate hands on how to videos! Trying to read a manual and focus on tiny pins or such...........whew, thank you sir for easy to understand info!

[@samuelparra1510]

Thanks for explaining how to test relays and demonstrating how they work. I really do appreciate it. I'll be looking forward to viewing more of your videos.

[@myRatchets]

Samuel Parra Glad to hear you liked it, thanks for commenting, cheers.

[@kellykemp9336]

Fabulous, great information. I didn't know 'come here from sickem' before viewing. I couldn't even use an Ohm meter and was able to conduct all the tests following your expert instruction. Thank you for your time and Service.

[@chalkywhyte8585]

Been trying to sort electrical problem on Suzuki quad..Thought a relay was ok because it "clicked". Thanks to your in depth video I now know that it is shot. No power to the light, so I pulled it apart and lo and behold, a blown part on the circuit board. Keep it up, you are good

[@myRatchets]

+Chalky Whyte Sweet, very glad to hear the video was helpful. Thanks for your comment. cheers

[@jd5787]

Thanks, I have a pair of relays in a wine fridge that may be problematic, I think your video did a good job at explaining how to troubleshoot these things! Thanks

[@green1394]

You are a good teacher my friend,,,,,keep up the good work,,,this world needs people like you,,,MaashaAllah,,,

[@interludo]

So clear. Wish all video tutorials on tube were like this. Thanks.

[@daveyusa1884]

this was an even better, maybe the best, explanation, thanks. my relay clicks, resistance goes to 0, but using a light on the terminal does not light up, a bad relay! without that light test, I would have thought it was good, thanks MUCH!

[@motoprophet3981]

Great video. I have a Lincoln LS that would not run. The relays all had good ohm readings and would click when tested. It was the last step that tested the pulled voltage, that revealed the two bad ones. Thanks.

[@mixedlife1691]

I love how detailed you have made this video! Thank you for taking the time to make this video for all of us that are trying to learn this kind of stuff! The only thing i have not been able to put 2 and 2 together on is when you are grounding as you are testing with the light what exactly are you grounding on? This is probably the simplest answer ever but chaos has had my brain scrambled so please enlighten me.

[@lukemartin7029]

This is the best video I've found on relay explanation. Thanks for posting.

[@myRatchets]

Luke Martin It got a bit long but alot of info in there for people with patience. Thanks for watching, cheers.

[@frigerzoid]

Luke Martin Agreed!, great demo and tutorial.

[@commonman80]

Where did you ground The Test Light in the 5 PIN Demo? To The Battery Ground?

[@froglegs4910]

He is the best auto professor The EXPLANATION SO CLEAR !

[@highlandminger4009]

May be an old upload, but it saved me from buying a fuel pump relay that I didn't need. Thanks

[@rplogix]

Yes as mentioned by other, the quality of your videos are amazing. Not only the image quality, but the setup, camera position, you explanations on the board, just great work.

[@michaelhorbovetz1820]

I appreciate the step by step instructions you gave on testing relays

[@cesararbelaez4695]

Hi body . Very useful your video . But I have the question my relay pas all the steps but my lamp go on touching 87 and 87a as well . That means the relay is bad ? Have a malfunction breach?

[@davidpettengill914]

Great video. Your explanation of how a relays works is spot on. Very easy to understand.

[@rplogix]

Hi, your videos and explanations are very clear and helpful for every one. Keep on your great work. I had a car starter that won't start so before I dismantle my ignition switch I will run your tests. Thanks a bunch!

[@nbo7383]

they only we can pay your effort sir not to escape the advertise in you video and subscribed..big help to the people!

[@davidsantiago3360]

Thank you. This is by far the best video explaining relays out in youtube

[@richarddybala2002]

Helped a lot to get my old tractor running again. Thanks.

[@chrisdowers7081]

BEST VIDEO ON HOW TO BENCH TEST. I HAVE SEEN . THANKS

[@robertovermier6200]

Great video on testing the three relay types. Came in handy when trying to determine which of two relays were faulty.

[@vincentesolon2210]

I really like you well informed and detailed videos. I currently also have a 1995 Toyota Camry with a cranks but not start weekly. I will have to look at the nss . Really thank you a lot for your many 1995 Camry videos.

[@CloudwalkerDrones]

great video. would also point out if you do not have a test light, you can use the multimeter to read volts between 30+ and 87. If you see a 12, you're good!

[@edmundochaparro-barriguete1215]

You are the man with the plan. Excellent video. Thank you so much. You really know your field.

[@frankfinney4304]

Best tutorial yet on how to test.

[@safetyalways7788]

My toyota 90987-t2003 relay resistance is 168 ohms. Tested up to 3 relays in my car. All same value. I think the resistance depends on the manufacturer of the relay and the amount of current designed to pass through to them. And all the relay are working well

[@lspalla65]

Thank you this was very helpful, the only thing I didn't have was a test light when I did your test. don't know how important this is to the test, but everything I did do showed the circuits to be working correctly.

[@gregvanderhorn8394]

This is a great video. I seriously mean that. I am in the middle of re-wiring my motorcycle and organizing a rat's nest of wire. This video has helped me greatly

[@thefaz10]

Well done sir, The explanation is clear and concise, the video is clear and easy to view. Following the steps for checking a 5 prong relay was cake walk. Great video !!

[@enkisonofanu2301]

Thanks for that, my relay does not have a diagram, but with your help, I can test it. 5 thumbs up.

[@trevorfrillman8842]

Awesome video! Had a problem with the car but couldn't narrow it down. This helped a ton!

[@alexandergonzalez2232]

Awesome learning from you the big concepts of integration and the detail points and patterns, it enhances my understanding, thank you!

[@michaeld9731]

Thanks for this information. You have saved me a whole lot of time and I am confident I’ll be able to test the relays for my radiator and a/c cooling fans. 👍

[@bucky2292]

best explanation of testing relays i ever seen ! good job mister !!

[@sanjaychaudhari8352]

This video is very easy to understand working is explained in very effective way

[@CesNwk10]

by far the best resource for checking relays out there good stuff dude

[@sroysr]

this is the best how-to video i've seen yet.

[@diegoG928]

Good explanation. Simple. Straight forward.

[@potterg04]

Great video 👍 I appreciate the facts about relays and how to test them correctly 👍

[@davidn3616]

On the five pin test, i would like to of seen a close - up of the pins, your touching and slow down a bit, Your one of the best

[@lehoa28]

Thank you very much. This video helped me diagnose my signal stork problem. 👍🏻

[@stephandelange1776]

Thanks for giving us good front view and explanation video on relays and how to test them, Good Videos really!

[@billc2381]

Well spoken, nice diagram(s), tools and easy to follow procedure. Thank You.

[@myRatchets]

Billy C np, glad you liked the video. thanks for commenting.

[@toantran1]

Thank you for showing me how to test a relay without a diagram. It's great !!!

[@jasonsmith6776]

Best relay vid on KZbin thanks

[@TheShady80]

Excellent Video and VERY informative !!! in no way "over kill"..... thank you so much for taking the time to explain every detail so thoroughly...Really appreciated !!

[@1506pinkers]

Excellent. A very clear and comprehensive video. Thank you.

[@TheLaidbackBiker]

Great video. You helped me confirm my 5 pin relay is good. Thanks brother!

[@michaeltempsch5282]

If the relay has a snubber/clamping/free-wheeling/flyback diode in paralell with the coil, then which way you connect 86 and 85 does matter. Connect it the wrong way around and you're likely to kill the diode by over-current. If the diode fails open (most likely) you now have a functioning relay without snubber diode (which upstream electronics might not appeciate). If it fails closed you've got a short across the coil and a non-working relay.

[@drummerboysmith968]

+Michael Tempsch I just watched this video and was about to post a similar response and decided to check if anyone else had picked up on his omission of the diode scenario.. Congratulations, sir. I give you a thumbs up. Hope everyone out there reads your comment.

[@ΠάριςΑζής]

The free wheeling diode is used in electronically driven relays, through the use of a driver transistor. The relay coil is the collector load of the transistor. When the C.P.U sends an energizing command to the driver transistor's base, the collector is practically grounded to the chassis and the relay coil gets energised. The protection diode, is connected in antiparallel way to the coil (i.e. its cathode connected to the battery voltage supply connection of the coil and its anode to the collector connection,that is, to the other terminal of the coil). The diode is therefore in reverse bias, which means that it does not conduct any current when the relay is activated. But when the driving command in the transistor 's base goes off, then the transistor comes in cut off, that is, it acts as an open switch. At that moment, a high spike of reverse polarity develops at the transistor 's collector. The free wheeling diode is forward biased to this spike, it comes in conduction and shorts this pulse to the battery's positive pole. In this way the driver transistor survives for many many operations. In car circuits now, the use of a pulse absorbing resistor is very common for (at least) two reasons. The first one is that the commands to the relays are usually given by hand operated switches. So the possible spike when the switch is off, is effectively absorbed by the resistor. Even if the resistor is not there, the spike will only cause arcing between the switch contacts when the circuit opens, but it will not destroy anything. No transistor there in danger. But the second reason is much more important. The use of protection diode makes the relay coil terminals polarity dependent which is not safe to use in car circuits. The reason is exactly the possibility of power supply reversal during connection which results in damage of the diode, rendering the coil unprotected and therefore a spike generator. In any case, the upstream electronics are not in danger as the energy developing during circuit break is dissipated as arcing within the switch contacts. In the long run, if there is no absorbing resistor or diode, the relevant switch will finally end up having high resistance in its contacts and perhaps will melt them completely. Another important point is that the evaluation of the good (zero ohms) contacts when closing cannot be done by the beeper of the multimeter. This will mislead you. The test needs to be done with the nominal load connected to the relay and then by measuring VOLTAGE across the contacts under test, using Ohm's Law for the evaluation of the test result. The multimeter 's beeper will show you continuity but it cannot give you any measure of current flow at all. This test is the most effective for any power switch...

[@ΠάριςΑζής]

@Do-iz6qd I am happy to see that my comment was useful information to you. As regards the testing of power switches in general, the best way is to test them under real conditions (dynamically) instead of using the beeper of a multimeter (because the beeper uses only some milliamperes for testing, which is a negligible amount of current in comparison to the current the switch must deliver to its load)...

[@wilmi79]

Best video of its kind, I found it very helpful. Thanks! I'm going to subscribe to this channel. If the other videos are as good as this, I will be very happy.

[@myRatchets]

+Michael Williams Welcome aboard, hope you enjoy the video's. cheers

[@thecelt4807]

fantastic tutorial mate ,,,greetings from australia

[@guitartricky]

I have a Bosch 5 pin micro-relay which is a little different than the first relay you tes but the diagram is essentially the same. I was able to use the same procedure tp test it. Thank you!

[@speedy_pit_stop]

I liked all the added details about relays.

[@kimma7135]

Wow. Extremely helpfull info. Thank you for showing us. Your video save me money and time !

[@jajimenez12214]

Must agree that is the best video I've ever seen.

[@harrywallace3556]

You did a "GREAT JOB SHOWING AND EXPLAINING" how to test a five pin Relay, with step by step instruction's. Keep up the good work man.

[@alawaady]

Thank you for the distinguished and useful explanation

[@bonitabonining6047]

your so nice..sir...this video of your's helped so many people to understand.. and to make it of thier own..thank you...😊...im bea from the philippines

[@PhanHung1973]

Thanks a lot. Very understandable. I am Vietnamese but I understood 95%

[@spelunkerd]

That's the best bench-testing relay video I've ever seen.

[@myRatchets]

spelunkerd Thanks for your comment spelunkerd, hopefully its not over kill, haha.

[@imatter4619]

I actually taught this guy everything he knows😀😀

[@Walkingcamel567]

great tutorial! Now I feel very comfortable testing any relay-Thanks again and keep up the good work.

[@jojozepofthejungle2655]

Fantastic, now I know what a relay is. The last video was just pictures, I'm thinking like wtf. Excellent video dude.

[@steveveness3829]

Very good explanation. Far better than my old rage teacher almost 37 yrs ago. Well done😉

[@DerekGHikes]

Thank you for the refresher, great knowledge... been a while since I've done this.

[@nigelkendall5892]

bit confused about relays until i saw this, this is a great video thanks

[@wolfythelobo]

Excellent explanation... I think I can tackle those relays now Mahalo for your time and effort to share your knowledge.

[@1905AdamH]

Utterly awesome vid! So concise and clear! Finally I understand!! Thank you so much!👌😀