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Turn Signals Not Working

3853 Views 16 Replies 6 Participants Last post by  EV Nerd
Hello all,
On my 2018 Clarity, the turn signals and emergency flashers do not work. For example, when I use the left turn signal, inside the car it flashes very quickly and nothing happens on the turn signal in the front or back of the car. For the right turn signal, the turn signal inside flashes quickly (and I am able to see the screen on the right hand side) and nothing on the front and back. I brought this to my local Honda dealer. The mechanic says it is not the fuses and is not really sure what it could be. His plan is to replace the Body Control Module to see if that will fix it. He ordered the part and it will arrive here next week. Any thoughts?
Tom
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Yes, happened all of a sudden. When I turn the car on, I get the message, "Headligh problem." Today, I just discovered somehting else. From the driver's seat, my left front headlight doesn't work. They both worked prior to bringing my car to Honda. Both headlights work on high beam. The tail lights and brake lights work fine. What a mystery.
Yes, happened all of a sudden. When I turn the car on, I get the message, "Headligh problem." Today, I just discovered somehting else. From the driver's seat, my left front headlight doesn't work. They both worked prior to bringing my car to Honda. Both headlights work on high beam. The tail lights and brake lights work fine. What a mystery.
Someone else (@[email protected]) posted something similar about a year ago. Turned out to be software. The infotainment software houses the software that runs everything not engine related, cameras, lights, etc…

Might be your issue as well? Dunno, but g’luck!
Someone else (@[email protected]) posted something similar about a year ago. Turned out to be software. The infotainment software houses the software that runs everything not engine related, cameras, lights, etc…

Might be your issue as well? Dunno, but g’luck!
Thanks, I will have the mechanic try that first and if it works, it will save me a ton of money!
Thanks, I will have the mechanic try that first and if it works, it will save me a ton of money!
I rebooted the infotainment software and no luck. I don't think it is a hardware problem. I am tempted to disconnect the 12V Battery, then reconnect it so that it will reboot the computer. I plan to connect a OBD II Vehicle ECU Emergency Power Supply Cable Memory Saver so that I won't lose my radio selections. Thoughts from anyone?
I rebooted the infotainment software and no luck. I don't think it is a hardware problem. I am tempted to disconnect the 12V Battery, then reconnect it so that it will reboot the computer. I plan to connect a OBD II Vehicle ECU Emergency Power Supply Cable Memory Saver so that I won't lose my radio selections. Thoughts from anyone?
I would think that using an OBD-II device to maintain 12V power in the electronics while the 12V battery is disconnected will likely keep the reboot from taking place. You could try it, then afterwards see if the car shows symptoms of having been rebooted, which is a bunch of ominous warnings about ABS, VSC etc. when you first start the car, those messages go away within the first mile of driving. Also your EV range will usually be very different (usually lower) as all of the past history that is used to calculate the EV range estimate is gone. Usually takes just a few drives for it to "relearn" and the EV range will be back to about where it was. Also the audio theft prevention will put a message on the infotainment screen telling you to press and hold the (audio) power button to reboot the audio system so that it can verify that the head unit is still in the correct car. If you don't get any of these symptoms after disconnecting the 12V battery then your OBD-II device probably prevented a reboot, so you would then need to do it again but this time without connecting the OBDII device, even though that means resetting your radio stations.
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I would think that using an OBD-II device to maintain 12V power in the electronics while the 12V battery is disconnected will likely keep the reboot from taking place. You could try it, then afterwards see if the car shows symptoms of having been rebooted, which is a bunch of ominous warnings about ABS, VSC etc. when you first start the car, those messages go away within the first mile of driving. Also your EV range will usually be very different (usually lower) as all of the past history that is used to calculate the EV range estimate is gone. Usually takes just a few drives for it to "relearn" and the EV range will be back to about where it was. Also the audio theft prevention will put a message on the infotainment screen telling you to press and hold the (audio) power button to reboot the audio system so that it can verify that the head unit is still in the correct car. If you don't get any of these symptoms after disconnecting the 12V battery then your OBD-II device probably prevented a reboot, so you would then need to do it again but this time without connecting the OBDII device, even though that means resetting your radio stations.
I chickened out of rebooting it. I called the Honda service and told them what I was about to do. They said rebooting it like a computer will not affect the Body Control Module. So, I have an appt on 5-20-21 to replace it. Will post after that. I thank you for taking the time to respond to this post. Your knowledge may come in handy for me in the future and also help someone else who reads this post.
I chickened out of rebooting it. I called the Honda service and told them what I was about to do. They said rebooting it like a computer will not affect the Body Control Module. So, I have an appt on 5-20-21 to replace it. Will post after that. I thank you for taking the time to respond to this post. Your knowledge may come in handy for me in the future and also help someone else who reads this post.
[email protected]'s problem turned out to be a bad connector. They also were past warranty and said the dealer had first tried replacing the lights at great expense. Did they tell you how much you are going to be charged for replacing the BCM? I would ask them if they have been in discussion with Honda about this and is it Honda's recommendation to replace the BCM. How far past the 3yr/36K warranty are you? You should call Honda and tell them what is going on and the symptoms and your concern that you are facing paying $xxx.xx as a first troubleshooting step. If you aren't too far past the warranty they may be willing to help.

I suggest read the linked threads below. There was another person Bleader99 who's problem sounded even more like yours, unfortunately after their first post asking for suggestions they never came back and reported what the solution was.


I just read [email protected]'s post again, the one in the "Headlights stop working" thread, and I think they are saying it was a grounding connector that was replaced.

Also their warranty situation is not clear, in one post they implied that they were past the warranty, and in another post they mentioned that the lights were replaced at huge expense. But later in that same thread they said there was "no charge beyond the $80 diagnostic fee on the first service for this complaint." Maybe what they meant is they paid for the replacement lights, but the dealer didn't charge them for replacing the connector beyond the $80 diagnostic fee.
Hello all,
On my 2018 Clarity, the turn signals and emergency flashers do not work. For example, when I use the left turn signal, inside the car it flashes very quickly and nothing happens on the turn signal in the front or back of the car. For the right turn signal, the turn signal inside flashes quickly (and I am able to see the screen on the right hand side) and nothing on the front and back. I brought this to my local Honda dealer. The mechanic says it is not the fuses and is not really sure what it could be. His plan is to replace the Body Control Module to see if that will fix it. He ordered the part and it will arrive here next week. Any thoughts?
Tom
You have a lamp out
JimO, you got it partially right. Got my Clarity back from the Honda dealer. Have a question after I explain what they said. Mechanic said the body control module was shorted out and needed to be replaced. They installed the body control module and discovered the short was caused by a faulty left headlight assembly. In other words, because of the moisture in the headlight assembly, it caused a short in the body control module. Does anyone know if this is true? Did I just get ripped off? This was an expensive repair. If I had replaced the headlight assembly and not the body control module, would the turn signals have worked then?
JimO, you got it partially right. Got my Clarity back from the Honda dealer. Have a question after I explain what they said. Mechanic said the body control module was shorted out and needed to be replaced. They installed the body control module and discovered the short was caused by a faulty left headlight assembly. In other words, because of the moisture in the headlight assembly, it caused a short in the body control module. Does anyone know if this is true? Did I just get ripped off? This was an expensive repair. If I had replaced the headlight assembly and not the body control module, would the turn signals have worked then?
Historically, when turn signal flashed very fast, it was a burnt bulb. The Flasher unit was a simple.plug-in metal can that sensed a reduced load Today they use leds. Regardless, it is in my opinion very unlikely that a faulty lamp would cause the module to fail as well - this of course would be a very poor design.

i hope a Honda expert has the definitive answer for you.
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Thanks for responding Jim.
Does anyone have any recommendations on how I could find out (as Jim mentioned) if a faulty lamp could cause the body control module to fail as well? I could ask another Honda mechanic, but they will most likely protect their own and not say anything. Or I could write the corporate office.

Regarding the moisture in the headlight, I take my car through the carwash at least once a week and I am thinking that maybe I had a headlight assembly that was not sealed properly.
I had the same problem: turn signals and hazards didn't work, and clicked at double time. Finally found that the HAZARD fuse was blown. I guess that the turn signals use the same electrical circuit; the Body Control Module must send different commands for turn signals vs hazards.

The HAZARD fuse is a 10A fuse in location g of fuse compartment B, in the cabin on the driver's side.
I had the same problem: turn signals and hazards didn't work, and clicked at double time. Finally found that the HAZARD fuse was blown. I guess that the turn signals use the same electrical circuit; the Body Control Module must send different commands for turn signals vs hazards.

The HAZARD fuse is a 10A fuse in location g of fuse compartment B, in the cabin on the driver's side.
In pre-CANBUS vehicles, a fast-clicking turn signal relay was a sure sign that a turn signal bulb was blown. The bulb filament was part of the turn signal relay circuit timing. In these old cars, adding a towed trailer's lights to the vehicle's lighting circuits would often mess up the turn signal timing, too. This is why there were turn signal relays specifically made for trailer applications, where all of the timing components were built-in to the relay itself. The relay didn't care what load was hanging off its output.

How times have changed.
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