How To Test and Diagnose Relays and Wiring [4 & 5 Pin]

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.

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[markiefufu]

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.

[teenice]

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!

[ramindadseresht]

You can even use a flat 9 volt battery and perform the tests. It worked for me. Excellent video man👍

[wiretamer]

Watch half a dozen of these, and yours is the one that worked for me. Thank you.

[kleenmaint]

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.

[artis]

This was a great and simple explanation of how relays works and how to troubleshoot if the relay is good. Thanks. Keep it up.

[markyakubovsky]

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..

[dancin]

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.

[seanmiller]

Great video! Smart and thorough! 5 star rating and thumbs up!

[edwardpurcell]

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

[jontnoneya]

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.

[topeka]

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

[jamdc]

This video goes straight into favourites,
thanks Tim, and take care.

[johnnielewis]

thanks a lot...and the key is infrequently review and/or practice this application in order to retain it... peace

[energy]

The best and most complete explanation I've seen. Thank you.

[tombryant]

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.

[DuelistMandroid]

Best relay testing video on the internet!❤ Thanks for sharing this.

[nicholasscurti]

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!!!

[louisroman]

Thanks for sharing, it's helping get out of the rabbit hole.

[victormendoza]

Loved this video show something how easy it is to test relay before replacing in a wrong way