How to test a Relay

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In this video I explain how to test a relay using a multi-meter and a square battery.
The terminals of a relay are numbered using an identification system known as DIN 72552. This system was developed in the German automotive industry and has since been adopted across the world as the standard method for labelling and identifying electrical terminals. DIN 72552 assigns a numeric code that clearly defines the function of each pin/ terminal in a relay. The table below shows the codes used in automotive relays.
85 Relay Coil Negative
86 Relay Coil Positive
87 Common Contact - Output
87a Normally Closed Contact (NC) - Output
87b Normally Open Contact (NO) - Output
88 Common Contact 2 - Output
88a Normally Closed Contact 2 - Output
88b Normally Open Contact 2 - Output
30 Feed/ Line In Positive
A micro relay is a smaller version of the more popular standard relay and are used when space is at a premium. Micro relays are more compact than the standard size and are an ideal choice when you need to save space - for example in an ATM fuse box set up with mini fuses. They have a smaller rectangular shape compared to the square cubed shape of the standard relay. Micro automotive relays use a different terminal number identification system compared to standard mini relays. See the list below for micro relay terminal numbering:
1: (4.8mm) Coil Positive
2: (4.8mm) Coil Negative
3: (6.3mm) Feed/ Line In Positive
4: (4.8mm) Normally Closed (NC) - Output
5: (6.3mm) Normally Open (NO) - Output
#Relay
#Howitworks
#automotive
#Mechanic
#test
#GarageTech

Опубликовано:

30 сен 2024

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Комментарии : 34

@LuisMartinez-fr9gq 2 года назад

One question friend if i do the jumper wire with a fuse and i want to test ECU relay 12 volts 50 amps is the relay, how many amps it has to be the fuse so i do not blow anything, would you please let me know, this is for pin 30 and 87.

@tevinmouton 3 месяца назад

This just helped me so much with trying to figure out what is going on with my Car’s A/C

@mattgreen9835 2 года назад

I was drunk when i watched this and i could easily follow along and understand (working on a 03 yamaha R1)

@HenryFMora 2 года назад

First video that I’ve run into w/o opinionated comments, good schematic, plus he stayed on the subject.

@DADSGETNDOWN 3 года назад

Who can build a replacement relay ? With a working sample, that is from 1983, motorcycle, it has the number and manufacturer on it, but noone makes them anymore, there is no diagrams that we can find no real information. I do have Details on where it goes to, and what goes to it etc and it does have a diode.

@GarageTechAutomotive 3 года назад

You could de pin it from the relay board and re wire with some wiring connectors to another 4 pin relay? Or you could hunt around some scrap yards etc.

@DADSGETNDOWN 3 года назад

@@GarageTechAutomotive Yeahm been looking at salvage yards. I heard there are issues with using just some relay because it's a start button relay that goes into a sensitive TCI Unit which is the Motorcycles early 80's Electronic Ignition and to the starter solenoid/relay. And the way it has a diode, and the Kickstand and neutral safety switch are designed and go into it. I still can't believe it would be that hard, but forums say different. Since I don't know relays or electronics THAT well, I am afraid to burnout the TCI which you can't buy anymore either.

@dangerdavefreestyle 2 года назад

outstanding tutorial. can you please discuss 87a? On mine it is closed when the relay is off and it opens when the relay is on while 87 seems to function like a regular switch, relay gets energized and pins 30 - 87 get continuity.

@GarageTechAutomotive 2 года назад

Hey, is yours a 5 pin relay? If you have a 5 pin relay then the switch is usually closed on pin 87a, so any power will go out on 87a. Then when the relay is energised it will switch to pin 87. These are typically a switch over relay for for switching power between two circuits. Hope that helps 👍🏼

@spiritbuu 2 года назад

4:55 I don’t get zero here, it’s fluctuates between 0.04 and 5.0 (a bit higher and lower too). Does this mean the relay is shot?

@GarageTechAutomotive 2 года назад

Hey, if you’re closing the switch manually, it should read .0 ohms sound like the contact on the relay are worn.

@spiritbuu 2 года назад

@@GarageTechAutomotive Yeah I get between 3 and 4 Ohms on each relay when powered by a 9V like your setup in the video. It does beep during Continuity test. Would this much resistance be okay or does it have to be 0? If it’s not ok, it is enough to not power the fuel pump? My fuel dash gauge doesn’t show fuel reading either. Thanks for your quick response.

@GarageTechAutomotive 2 года назад

@@spiritbuu yes that could cause it not to work, have you checked what voltage you’re getting at the fuel pump? Are you using the 9v battery to close the relay and checking the resistance on pins 30 & 87 at the same time? A continuity check will just confirm that there’s a connection but not how good the connection is, that’s why a resistance check is better. If you can, test this, with the relay plugged in and the circuit on, check for 12 volts at pin 30, should be min 11.5v depending on battery condition, and then check at pin 87, it should be the same. If it’s not, the relay is definitely shot. You could use a jumper wire to bridge the relay, just double check you are getting the right pins otherwise you could cause some damage. Good luck 🤞🏼

@chimbo8741 3 года назад

When I set my multimeter to ohms it reads 0.L, not 1. Am I doing it wrong lol?

@GarageTechAutomotive 3 года назад

Hey, different multimeters can display different readings for “open circuits” OL means open loop, so no connection is detected between the two probs, it should change to 0 if you touch the probes together.

@heyyou1059 2 года назад

Awesome video. Very explanatory

@DesertMarineZ 2 года назад

Thank you my dude, I could not figure out how to test the relay since my multimeter fuse is blown. Click Click. Does anyone know what the external relay kit is called? My ASD got corroded and I tried to solder it but its not holding a current. Got one from the junkyard and it has the same problem on the same pin (control side)

@juliondariomedina5598 2 года назад

You are too Smart 🤓

@bentramell729 2 года назад

Turn the dsmn thing towards us so we can see the pin configuration that you're touching things too. By mine your connecting 85 and 87

@ianwilliams1448 2 года назад

Nicely explained

@sline3660 4 года назад

Thank you so much 🙋

@kevinmccullough3199 3 года назад

Interesting, thanks. I need to make up a diagnostic test for a Saab 900 classic, depending on the car some have a test connector the error codes can be read here but how do I wire it up? One side of goes to the fuel 87b relay + two other 0.75 wires go to? Do I use the relay side or? Presumably the switched connector is to the earth side, can you clarify this?

@zuberilol 2 года назад

So I'm assuming if I want a toggled power source for a low powered device I could put a 12v on/off switch to 86, ground to 85, my device on 30, a 12v power to 87 and ignition circuit power to 87a? Or can I not do it this way?

@zuberilol 2 года назад

FYI: This is so my device can be auto powered when ignition is turned on, or controlled via a on/off switch.

@gulabkeerio1930 3 года назад

good job

@danielrossi5160 3 года назад

@GarageTech Fantastic Video, thank you so much. I have a question: would you be able to tell me what model of Relay was that one that you used in this video?

@manlaibaatarganzorigt9049 4 года назад

You do a fantastic job of explaining subject. Keep it up!

@alfredo8431 6 месяцев назад

All I can say is wow 👍

@antonmur 3 года назад

Great video, easy to understand and follow. Question, how come you cant check for continuity through pin 86 and 85 but you can check for resistance? Has it got something to do with the power the multimeter is sending? Thanks

@GarageTechAutomotive 3 года назад

Hi Anton, you could check for continuity but that check would only tell you that there’s a connection between the two. A resistance check is much more reliable because if there’s a large amount of resistance, let’s say from corrosion, the resistance check would pick that up and that could be why the relay is not closing the contacts correctly. The continuity check would seem ok and you could miss where the fault is

@antonmur 3 года назад

@@GarageTechAutomotive Thank you. I assume the level of resistance applied is the reason why you sometimes get a beep or not (continuity)/ The resistance going through the coil of the relay is generally high.