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 was a good video because it’s for visual learners. Your context helps people who like to read but not people who can concentrate. Granted theirs good info it doesn’t help at all for some people, perhaps you can also start a RU-vid channel to share and explain?
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.
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.
Thank you. While this young man is great and I've been learning alot, you read my mind on the little pins, and where they went. Being a beginner I'm soaking up all the info I can. I went on your channel to see if you had any instructional videos on Multimeter checking. To me that is the most daunting as it's so specialized. Repairs of the body of the vehicle and all the other things are great but am looking for more videos on this very specialized information...multimeters and how to check fuses, relays, and wires, etc so we can figure out why our power goes south in our car batteries, despite starting out with a strong and new battery. God bless.
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.
Also not to forget, temperature plays a critical role in this. Some relays will act up jerking when the engine bay is hot. Under heavy traffic or traffic jam (stop and go traffic) or also under low freezing temperatures. So those cases are a little bit harder to diagnose because basically you want to wait until those conditions happen to test them. It once happened to me. Just my 2 cents.😁🙃😜
@@joecualquiera Amen to that ! . I replaced all the relays on my 1987 BMW M6 with Tyco and Bosch relays for prevention of possible problems. Then I started getting full throttle power surging. The new fuel pump relay appeared to cycle open -closed under load and hot southern climate. Put old one back in - problem solved. Maybe the diode-resistor combo on the new Brand A relay was a little different than the original Brand B relay.
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!!
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..
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!
also the schematic on his relay cover shows a diode, so above 85 there is an arrow pointing to a line, the arrow side is positive the line side is negative
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.
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
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.
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.
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 .
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.
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!
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!
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.
I used to do that at the parts store to test both relays and headlights. Gotta make sure it's a strong one, though. Nine volts is only 75% (or less) of what the relay is built for and a weak battery may not be strong enough to flip the switch. In the store I would test the old and new one just to be sure I wasn't getting a false result due to the lower voltage.
If one is not skilled using a multimeter then the next best thing is switching a known good relay to see if the failure persist. Your video is really good,well explained
This a step in the right direction. You should really use something other than an ohm meter to check the contacts. It's possible for the meter to tell you the contacts are ok but the contacts fail under a real load like a light bulb.
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.
Correct terminology of a relay, solenoid, or contactor. Normally Open N.O Normally Closed N.C. Common (basically the part of the armature that has constant power to it- depending if its a single or double throw set of contacts. Armature- the little copper arm that gets pulled down when powered to change states, then spring returns back to de-energized position. Coil- Literally a coil of wire (A1 & A2). When voltage is sent on the hot side (or negative side if its a DC coil), current flows through and creates a magnetic field just like a motor or transformer, which pulls the armature down to switch states on the contacts and keeps it in position until the signal being sent to the coil is switched off. Hope that clears some things up. There's a ton of other details about control devices like these but this is the basics... Terminology matters in this field of 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!!!
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.
It's called an armature. The switch inside that opens and closes due to magnetism of the circuit when power is supplied. This video is helpful but may be confusing to many foreign car owners. The testing circuit isn't always 85-86. You need to carefully read the schematic on the side of your relay. 87 will always be open, on some relays 86 is a ground, on some it is hot and carries a voltage and on others even more confusing it is completely unused. Like certain VW's for instance. The easiest way to realize that 87 will always be open, so on a 4 pin relay that leaves 85,86, and 30. Usually on most relays 30 will be hot, son on foreign vehicles that don't use pin 86 the power circuit will be 30 to 85 which will close the 87 circuit and send voltage out. Because all relays especially on foreign cars are different you really need to learn to look closely at the schematic on the relay and not be so trusting of these videos.
What if it’s a 5 Point Relay, from a 1991 Lincoln Mark Vll & there’s no schematics on the outside of the Relay? The Relay in this video is from a vehicle more current than my 1991.
@@7777Lace I would look the information up online, or I suppose you could just try all of the different pin variations to see if you hear the armiture kick over when applying 12v with low amperage. I've never seen a relay without any markings. It must be generic, you could try looking up a brand or stock relay to get a better picture. Most all stock relays will be marked. Best of luck!
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.
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
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...
Wow. You just saved me some frustration. Not less than 3 minutes ago, my 98 accord's condenser fan relay clicked - tho' the condenser doesn't work w/o bypass to battery. THEN I saw your resistance test - bam. No change from the 1! Thank you for this.
Relays that work of the cars computer may have a different voltage than 12 volts to the relay. Typically around 2, or 5. Not sure if giving 12 volts across the terminals will damage the windings in the realy.
Pretty cool. I've just bypassed the relay before to see if it was working. If it works then relay is bad if nothing happens something else but still could have a bad relaybut this is cool also. My grandfather had a truck and the garage told him fuel pump was bad so I replaced it not testing it first thinking the dealership knew what they were saying anyway the new one didn't work so I bypassed the relay and it worked, put a new one in nothing tried relay in another spot that worked just not fuel pump lol. I eventually put the relay back in and run a jumper from the remote wire on the safety shut off relay to the fuel pump relay and it worked for 6 years no problem when he traded it in lol.
thanks, your demonstration worked for me. the only thing I was not clear on was the positive side connection, and I found that in a comment, well explained, herein. other question was does it have to be 12v power supply for a 12 volt system relay? reading comments, not really.
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.
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.
dear naveen av as we talked there is resistance between in your relay as your scooter all relays prety much works the same way good luck w your scooter.
That is cool. I just learned that if your horn works, you can swap your horn relay with the fuel pump relay and see if it starts if you're trying to diagnose a bad fuel pump relay. 🤙
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!
Well done. Your technique ia correct and your information is as well. Don't let these negative comments get to you. Even when you use incorrect terminology you get your point across. That is what is important and that is the bottom line.
Good job, but a voltmeter will not put a current load on 30 & 87. You could still have a bad relay. What if the contacts are burnt? You would have to load the relay and do a voltage drop test in order to see if the contacts have high resistance.
The information was great. Instead of trying to hold the relay and the tester, leave the tester on the floor. If it is straight and flat, the display can be seen. That way, theirs no chance of you dropping the tester.
i believe they now have solid state relays so there will not be a click. in both cases hook a multimeter / DVM to the circuit that will be completed 30 & 87. Put the DVM on ohms. before you energize the two contacts 85 & 86 for the solenoid, dvm on oms should read infinite resistance b/c the circuit is open. when 85 86 are energized, the DVM should go to zero or close to zero ohms.
fabio sarmento: "I've always been teached that we never measure resistance in an energized circuit. Can you explain me how it is possible? thanks" This is generally a good way to burn out your ohm meter. With relays it's kind of a moot point since rarely do they connect the coil lines to the switch pins since you can just do that on the printed circuit board, anyways. If you want to be sure it's safe, set the meter to volts first and make sure there's a 0 reading. Then you (probably) won't damage your meter. I tend to use $3-5 meters for ohms, anyways. Best not to use a $100+ meter for ohms on a circuit with a battery/AC/large charged capacitors on it.
