Important note: some relays are controlled by a module or computer inside the vehicle, and can be damaged when checking for power/ground with a test light in the vehicle if too much current is pulled through the circuit. Although most incandescent test lights will not hurt a computer controlled circuit when used properly, the possibility does exist. If you follow a wiring diagram and the wire goes back to a computer or module (or if you are not sure), you may want to use an LED test light for your power/ground checks.
i have changed the fan and all is working fine thanks ,what a pig of a job on right hand drive cars thanks alot honda lol they qouted £460 .cost me £40 for the part from salvage yard
my honda civic 1996, relays are good, sensors are good, but my mechanic thought that the thermo fan switch sensor is the knock sensor. he couldn't wait for replacement he turns over to me the vehicle and then , when i turn on the switch, my radiator fan run automatically.
if relays are damage did it take the radiator fan to run when the switch is ON sir?my relays are good, and sensors, thermosensor/ fan switch, thermo switch, ect sensor.
Great video, my question is can I throw power to 87 socket to see if an ac compressor is engaging. So I guess what I'm asking is can I take my power probe, stick it in 87 slot, throw power, and see if the ac clutch is engaging, is that safe, seems logical to me but I'm far from a mechanic or electrician, but my son's ac isn't working and trying to rule out any issues. Thanks and great video
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Hi, would you mind telling what those relays are for that are located right under the Steering Wheel? My Honda Accord is 2017 sport special edition. I would appreciate your help .
hi, my accord 2009 idtec, no dash light, steering wheel, all buttons work, can tell wich is the relay for dash light, all fuses work, light, locks.. thank you !
My 2011 Honda civic drivers side turn signal is going super fast. Bulbs are blinking. The passenger side is fine. Then if I push the Hazzard button everything works fine. Does the car have a relay on each side or one relay for both sides. I even changed the bulbs. Im.looking for answers, do you have any ideas? Thanks.
I tested pin 3 and 4 for short and it is shorted. Can I use that test to see if the relay is good? Is it supposed to be shorted? I would think not because none of the others short at pin 3 and 4. I am testing specifically the fuel pump relay from under the dash. I swapped it out because I think it is shorted and it blew out my fuel pump. But now I get a check engine light with codes P0135 and P0498 with the new relay. So either got a wrong replacement relay or the old one was good?
my aircon doesn't work, someone suggested a faulty aircon relay ? in order to test it i took out another relay and put in in the slot where the air con relay was, no different aircon still doesn't work . So i put the relay back where i got it. After that i get check engine warning light and having problems with my idle speed . Anyone got some advise ?? Did i messed up the relay by trying it in the aircon slot ??
Thx for the great tutorial. I have been a fan for a while. My AC on 2007 Honda Civic Hybrid does not blow cold air. Compressor clutch engages for a bout 2 second and it drops off for a about a minute and cycle repeat itself. Radiator Fan and Condenser Fan do not go on during this time. Using a Probe, I checked the Radiator Fan Relay circuit as you recommended and uncover that I do not get power on terminal 4 socket. All other sockets checked out Ok. I appreciate any recommendation.
Hard to tell from your description exactly what you are seeing, but heat (burned relay or relay terminals) usually indicates resistance. It could be a few things, but the first thing I would look for is corrosion/green crusty crap/loose or bent terminals at or near the relay (sometimes it is difficult to see because they are all in a power distribution box). I would also look for a partially broken/corroded wire near the relay. All these things can cause the voltage to not flow through connection properly (and instead create heat).
Do you know what the rest of the relays are to the right of the blower? I know one is the horn. But what are the 4 with the manual symbol next to them? The manual doesn't say. Thanks!
Relays from left to right looking at box from front of vehicle: 1-Blower, 2-Horn, 3-PGM-FI Main, 4-PGM-FI Sub, 5-Ignition Coil, 6-Throttle Control, 7-(at right end of box) Rear Window Defogger. Directly underneath Blower relay is the A/C Compressor Clutch Relay.
The starter cut relay on those Civics get both power feeds through the ignition switch in the Start (number III) position ONLY. The ground is supplied by either a clutch interlock switch or a transmission range switch depending on transmission. I would start by getting a free wiring diagram for that vehicle from BBB Industries website and test the circuit and find where I am losing power (or ground). Jiggling the ignition switch in the start position while keeping a test light on the relay sockets that should have power can help identify a bad ignition switch. Doing a similar test while moving transmission from park to neutral (or pressing the clutch) can identify a bad transmission range switch/clutch interlock switch. Obviously all fuses and connections between starter and battery need to be good and the battery needs to be good as well.
nice video helpful ,i have a I have an 07 Honda Civic 1.8 mk 8 ,i have a problem with my blower motor fan ,it just comes on when it wants and i seem to get all speeds when it works and full heat,i have replaced the switch on dash ,still same problem could it be my relay fuse is bad thanks.
It is possible that the relay is going bad but it will need proper troubleshooting done (needs to be done when the blower is NOT working). Here is a video where I troubleshoot an Accord, it has a similar electrical blower motor set up to those Civics. ruclips.net/video/ZCFiuhgSkFE/видео.html
Hi. I need some help please. I've got a civic 2005 and the left side window only goes down ( car is RHD) . Ive checked the switch,fuses , motor, the tiny white box on the door panel ,cable from the door and all work. The way I've tested it is to do a switch of every component and check it at the rear left door. I've checked each of the cable ends with a multimeter on the ohm setting ( the one that beeps if cable ok) and is ok. Even checked the master switch button for the side that doesn't work and is ok. Fuses ok everything ok. Haven't checked the relay ,but since is just one for the windows, I presume it doesn't affect just one side. Fuses ok. Everything ok. The only thing I forgot to mention is that the window only goes down. Any ideas please. Or suggestions. I'm stuck
If I was troubleshooting it, I would go to the window regulator itself and unplug it and use a simple test light in place of the window regulator (motor) to see if it will light up the test light when the window switches are pressed in both directions. That way I could tell if I am getting enough power to the circuit (a loaded test). Testing with a multimeter is ok but does not load the circuit. If the test light lights up in both directions (up and down on the switches) then it is most likely a bad window regulator. If it only lights up going in one direction (down in your case), then a bad switch (or master switch) is most likely the culprit. There could be other issues but those two are the most common. Swapping components to test is ok but the circuit with the problem needs to be tested under load and you can't really do that by moving components. There should only be one relay for the windows on those Civics and if it was bad then none of the windows would work.
Not enough info, there are multiple reasons why they can do that but without knowing year make and model I wouldn't even be able to steer you in any direction.
That is not a standard relay system like a blower motor or something like that. The wiper relays (3 relays) are part of the Relay Control Module, which is integrated into the under hood fuse box. The relays are not serviceable individually. These systems are not easy to troubleshoot due to their complexity. The wiper switch (called the Combination Switch Control Unit), the MICU (Multiplex Control Unit), and the Relay Control Module all communicate over the B-CAN Network (Body Controller Area Network). Checking these usually requires a Honda Factory capable scan tool. That being said, power checks can be done with a simple test light or multimeter. With KEY ON, there should be battery voltage (power) on fuses 7, 11, 20, 21 in the under DASH fuse box.
Your video is very helpful, thank you. I have an 07 Honda Civic 1.8l, and the fans turn on with ignition. Radiator fan cycles as well while driving, causing the rpms to fluctuate. I have tested both fan relays and trying to test the circuit at the fuse box although, I am unsure how I probe correctly with a volt meter; is it the same as testing the relays? Any bit of information would be usual thanks.
Thank you for the comment. Some of these Honda cooling fan systems have 3 relays, a Radiator Fan Relay, an AC Condensor Fan Relay and a 5 pin Fan Control Relay (which is similar but not exact to the relay in this video). All 3 relays need to be working. The fans are also controlled through the ECM (engine computer) which receives input from the Engine Coolant Temp (ECT) sensors (2 of them). I would use a scan tool to look at the temps that those ECTs are reporting to ECM (look for temps that are weird, like say above 200 degrees on a cold engine). See my Civic P0128 video for shots of ECT temps on a scan tool. Of course wiring problems will cause havoc on any system so that is always a concern when checking electrical problems. Good luck!
I'm the original owner so everything is stock, I did change out the a/c compressor tho.. but, that shouldnt cause constant power to the fans..? I'll have to check out your other video, thank you again.
![How To Test and Diagnose Relays and Wiring [4 & 5 Pin]](http://i.ytimg.com/vi/S-DwV0HLsE4/mqdefault.jpg)
Important note: some relays are controlled by a module or computer inside the vehicle, and can be damaged when checking for power/ground with a test light in the vehicle if too much current is pulled through the circuit. Although most incandescent test lights will not hurt a computer controlled circuit when used properly, the possibility does exist.
If you follow a wiring diagram and the wire goes back to a computer or module (or if you are not sure), you may want to use an LED test light for your power/ground checks.
i have changed the fan and all is working fine thanks ,what a pig of a job on right hand drive cars thanks alot honda lol they qouted £460 .cost me £40 for the part from salvage yard
my honda civic 1996, relays are good, sensors are good, but my mechanic thought that the thermo fan switch sensor is the knock sensor. he couldn't wait for replacement he turns over to me the vehicle and then , when i turn on the switch, my radiator fan run automatically.
if relays are damage did it take the radiator fan to run when the switch is ON sir?my relays are good, and sensors, thermosensor/ fan switch, thermo switch, ect sensor.
Great video on how to diagnose problems even 5 years after you made this. Fantastic job!
Very well done. So clear, precise and to the point. Thank you.
I appreciate the comment, thanks!
Thanks for the info. You can also use a 9V battery to energize the coil, and check for the relay closing with the meter.
👍
Hi and thank you for nice simple explain.. With best way...
Good work
Thanks 👍!
OUTSTANDING VIDEO!!!!
Great video!!! Thank you. I was just wondering how I would go about checking the ground at the box where relay sits without a power probe??
A simple automotive test light works great for testing grounds (and power too).
Great video, my question is can I throw power to 87 socket to see if an ac compressor is engaging. So I guess what I'm asking is can I take my power probe, stick it in 87 slot, throw power, and see if the ac clutch is engaging, is that safe, seems logical to me but I'm far from a mechanic or electrician, but my son's ac isn't working and trying to rule out any issues. Thanks and great video
wont you get a ground signal on number 2 on some relays as that finds a ground path through the device somtimes?
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Thise video is incomplete is missing a hom resistant test because sometimes it gets hot and failed
Outstanding video.
bevil45181 Thanks!
Hi, would you mind telling what those relays are for that are located right under the Steering Wheel? My Honda Accord is 2017 sport special edition.
I would appreciate your help .
hi, my accord 2009 idtec, no dash light, steering wheel, all buttons work, can tell wich is the relay for dash light, all fuses work, light, locks.. thank you !
Great explanation. Thx
I don’t have a wiring diagram. Can I assume the relay will function either way positive/negative (then check the contacts with an ohm meter).
My 2011 Honda civic drivers side turn signal is going super fast. Bulbs are blinking. The passenger side is fine. Then if I push the Hazzard button everything works fine. Does the car have a relay on each side or one relay for both sides. I even changed the bulbs. Im.looking for answers, do you have any ideas? Thanks.
I tested pin 3 and 4 for short and it is shorted. Can I use that test to see if the relay is good? Is it supposed to be shorted? I would think not because none of the others short at pin 3 and 4. I am testing specifically the fuel pump relay from under the dash. I swapped it out because I think it is shorted and it blew out my fuel pump. But now I get a check engine light with codes P0135 and P0498 with the new relay. So either got a wrong replacement relay or the old one was good?
my aircon doesn't work, someone suggested a faulty aircon relay ? in order to test it i took out another relay and put in in the slot where the air con relay was, no different aircon still doesn't work . So i put the relay back where i got it. After that i get check engine warning light and having problems with my idle speed . Anyone got some advise ?? Did i messed up the relay by trying it in the aircon slot ??
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Thanks so much
👍
Thx for the great tutorial. I have been a fan for a while. My AC on 2007 Honda Civic Hybrid does not blow cold air. Compressor clutch engages for a bout 2 second and it drops off for a about a minute and cycle repeat itself. Radiator Fan and Condenser Fan do not go on during this time. Using a Probe, I checked the Radiator Fan Relay circuit as you recommended and uncover that I do not get power on terminal 4 socket. All other sockets checked out Ok. I appreciate any recommendation.
Sounds like you may have more than a bad relay, I suspect the A/C system may need some troubleshooting done on it unfortunately
Thanks so much, this is very informative.
Thanks for the comment!
Thanks for your time bro !!!!!
Thank you for the comment!
What ohm reading we looking for when there is power going to the relay?
Should be as close to 0 Ohms as possible, the spec for relays and switches that I like to use is generally less than 1 Ohm.
Nice! Thanks.
Thank you for the comment!
thnx for the post, its really helpful. i got this problem 2nd time relay getting burnt ,what should i do to over come if it repeats. best regards.
Hard to tell from your description exactly what you are seeing, but heat (burned relay or relay terminals) usually indicates resistance.
It could be a few things, but the first thing I would look for is corrosion/green crusty crap/loose or bent terminals at or near the relay (sometimes it is difficult to see because they are all in a power distribution box). I would also look for a partially broken/corroded wire near the relay. All these things can cause the voltage to not flow through connection properly (and instead create heat).
Do you know what the rest of the relays are to the right of the blower? I know one is the horn. But what are the 4 with the manual symbol next to them? The manual doesn't say. Thanks!
Relays from left to right looking at box from front of vehicle: 1-Blower, 2-Horn, 3-PGM-FI Main, 4-PGM-FI Sub, 5-Ignition Coil, 6-Throttle Control, 7-(at right end of box) Rear Window Defogger.
Directly underneath Blower relay is the A/C Compressor Clutch Relay.
07 cvic.. using a test light in the start cut sockets (all 4) I get nothing.. car won't start or crank? Any idea where to start..
The starter cut relay on those Civics get both power feeds through the ignition switch in the Start (number III) position ONLY. The ground is supplied by either a clutch interlock switch or a transmission range switch depending on transmission. I would start by getting a free wiring diagram for that vehicle from BBB Industries website and test the circuit and find where I am losing power (or ground).
Jiggling the ignition switch in the start position while keeping a test light on the relay sockets that should have power can help identify a bad ignition switch. Doing a similar test while moving transmission from park to neutral (or pressing the clutch) can identify a bad transmission range switch/clutch interlock switch. Obviously all fuses and connections between starter and battery need to be good and the battery needs to be good as well.
nice video helpful ,i have a I have an 07 Honda Civic 1.8 mk 8 ,i have a problem with my blower motor fan ,it just comes on when it wants and i seem to get all speeds when it works and full heat,i have replaced the switch on dash ,still same problem could it be my relay fuse is bad thanks.
It is possible that the relay is going bad but it will need proper troubleshooting done (needs to be done when the blower is NOT working). Here is a video where I troubleshoot an Accord, it has a similar electrical blower motor set up to those Civics. ruclips.net/video/ZCFiuhgSkFE/видео.html
Hi. I need some help please. I've got a civic 2005 and the left side window only goes down ( car is RHD) . Ive checked the switch,fuses , motor, the tiny white box on the door panel ,cable from the door and all work. The way I've tested it is to do a switch of every component and check it at the rear left door. I've checked each of the cable ends with a multimeter on the ohm setting ( the one that beeps if cable ok) and is ok. Even checked the master switch button for the side that doesn't work and is ok. Fuses ok everything ok. Haven't checked the relay ,but since is just one for the windows, I presume it doesn't affect just one side. Fuses ok. Everything ok. The only thing I forgot to mention is that the window only goes down. Any ideas please. Or suggestions. I'm stuck
If I was troubleshooting it, I would go to the window regulator itself and unplug it and use a simple test light in place of the window regulator (motor) to see if it will light up the test light when the window switches are pressed in both directions. That way I could tell if I am getting enough power to the circuit (a loaded test). Testing with a multimeter is ok but does not load the circuit.
If the test light lights up in both directions (up and down on the switches) then it is most likely a bad window regulator. If it only lights up going in one direction (down in your case), then a bad switch (or master switch) is most likely the culprit.
There could be other issues but those two are the most common. Swapping components to test is ok but the circuit with the problem needs to be tested under load and you can't really do that by moving components.
There should only be one relay for the windows on those Civics and if it was bad then none of the windows would work.
I really appreciate your time . I'll buy tomorow a light test and I'll go from there like you've suggested. Many thanks
My Radiator fan is turn on Automatically when i ON the starter. Please any idea why this happened.
Not enough info, there are multiple reasons why they can do that but without knowing year make and model I wouldn't even be able to steer you in any direction.
@@BigDog50001 my honda civic model 1996
Can you tell me,where the headlight relay located on my 08 Honda Odyssey? Thank you....
On those Odysseys, the High/Low relays for the headlights are built into a Relay Control Module which is part of the under HOOD fuse box.
Big Dog50001 Automotive thank you
Podrías mandarme el web de el checador de relevador
CAN YOU SHOW WHWERE IS WIPER RELAY FOR ACCORD 2003-2007 OR IT COULD BE IN ANOTHER YEAR ACCORD?
That is not a standard relay system like a blower motor or something like that. The wiper relays (3 relays) are part of the Relay Control Module, which is integrated into the under hood fuse box. The relays are not serviceable individually.
These systems are not easy to troubleshoot due to their complexity. The wiper switch (called the Combination Switch Control Unit), the MICU (Multiplex Control Unit), and the Relay Control Module all communicate over the B-CAN Network (Body Controller Area Network). Checking these usually requires a Honda Factory capable scan tool.
That being said, power checks can be done with a simple test light or multimeter. With KEY ON, there should be battery voltage (power) on fuses 7, 11, 20, 21 in the under DASH fuse box.
thank you great video
Thanks!
well made video
Thank you.
One man’s flip is another man’s flop. 🤷🏼♂️
Your video is very helpful, thank you. I have an 07 Honda Civic 1.8l, and the fans turn on with ignition. Radiator fan cycles as well while driving, causing the rpms to fluctuate. I have tested both fan relays and trying to test the circuit at the fuse box although, I am unsure how I probe correctly with a volt meter; is it the same as testing the relays? Any bit of information would be usual thanks.
Thank you for the comment. Some of these Honda cooling fan systems have 3 relays, a Radiator Fan Relay, an AC Condensor Fan Relay and a 5 pin Fan Control Relay (which is similar but not exact to the relay in this video). All 3 relays need to be working.
The fans are also controlled through the ECM (engine computer) which receives input from the Engine Coolant Temp (ECT) sensors (2 of them). I would use a scan tool to look at the temps that those ECTs are reporting to ECM (look for temps that are weird, like say above 200 degrees on a cold engine). See my Civic P0128 video for shots of ECT temps on a scan tool.
Of course wiring problems will cause havoc on any system so that is always a concern when checking electrical problems. Good luck!
I'm the original owner so everything is stock, I did change out the a/c compressor tho.. but, that shouldnt cause constant power to the fans..? I'll have to check out your other video, thank you again.
Excelent!!!
Thank you!
Ok,because people are stupid and give it a 👎,I'm giving it a 👍
Thanks lol!
Bollocks!! It ain't my a/c relay then!!😭😭
lol
👏👏👏
Thanks!