How to determine if mirrors on Honda Fit are being heated?
 

According to the manual for my 2013 Honda Fit, the button for the rear windshield defoggers also heat the side mirrors. Is there any way to confirm that the side mirror heating is actually working? I can't feel anything when I put my hand on it.

The background to this situation is that my car was parked in a 3rd level sub-basement last year, and it was flooded. The remediation took so long that it was spring by the time I got my car back. Part of the remediation was to replace the electrical wires and modules. A few things got overlooked, e.g., reconnection of the trunk lights. When winter came back this year, I thought that the rear defogger wasn't working and Honda did tests to show that it did. It turned out that the defoggers just aren't that effective on the Fit, taking a long time to heat the windshield. It took a lot of effort to have Honda check it, however, and I just didn't have to energy to bug them more about checking the side mirror heating (even though I did mention my concern about it when I complained about the rear defogger). As you might imagine, I have no desire to impose on them further to check the side mirrors if there is a way for me to check them myself.

See if the snow melts on the mirrors when you turn on the rear defogger!

I often brush off the snow before driving off, for the sake of safety. As for not brushing off the snow and keeping the car mostly stationary, the manual advises against that because it kills the battery.

It's often not snow that I'm worried about, but mist or fogging. I find that the defogger helps a bit with mist on the rear window, so I'm hoping to have that benefit on the mirrors.

*Should* one be able to feel the warmth of the heating on the mirrors?

Stupid me.
I didn't realize the rear window defrost also turned on a side mirror heat function. I rarely use the rear window defrost because for whatever reason the window stays pretty clear. But I've been complaining about how bad the side mirrors are on the Fit since getting it. Wishing it did have a side mirror defrost function.
Now there is a good reason to use the rear defrost.
You know I read my owners manual, I just must of missed it.
Thanks. Learned something new.

Glad to know that my problem is actually doing some good!

I have a 2014 (same as US 2013) and I wondered about it as well. It is very obvious to me when the rear defogger is running as I can see the lines warming up in the frost... but less so with the side mirrors. I find water spots remain and small chucks of snow too... hmm... how to test with a multimeter without taking the whole damn thing apart?

The heater in the mirrors will only melt ice and snow on the mirror itself, not on the cover or other parts. At least this is what happen in my car...

In response to the suggestions given on Stack Exchange, I was going to throw some snow on the mirror face and see if it melted. Tonight, however, the weather cooperated and coated the mirror with freezing rain. I drove for 20 minutes, the first 10 on the highway. The ice melted away. It's not ideal, however. There's a margin around the lower and right border where the ice seems to persist:
https://cimg0.ibsrv.net/gimg/www.fit...05122290a.jpeg


I recall noticing that region being particularly coated with frost in the past, when I was still wondering whether the heater worked at all. I suspect, however, that this imperfect heating isn't due to the flooding. Perhaps the solution is just a matter of replacing the mirror.

You must be on the east coast? We also got the freezing rain last night.

East-ish. Ottawa, Ontario.

USDM Fits did not get the heated mirror option till the 2015 GK, and only on the EX-L model. The CADM Fits I believe were standard on all trims down to the DX. The older gens cant say for sure for our CAD neighbors if it was standard feature or not.

If you do have heated mirrors, they should get warm to the touch if they have the heated grid underneath it.

Thanks, BassGuitarist1985. Just wondering, did you try it to confirm that the warmth is detectable? On another forum, they said that the mirror is heated to only a few degrees above zero, and I won't feel it. I know that I don't feel anything, but the photo above shows that it works, though there seems to be a problem along the right and bottom edges.

It makes sense that they would fit heaters on Canadian models, due to the winters here.

If it helps below, I made a video about this. At 5:18 I discuss and show the amperage draw of each mirror. at 5:38 i touch the mirror and it is warm to the touch yes.I can confirm the heating grid does NOT go all the way to the edges. In fact you can see it when it begins to defrost that the outer edges are not covered with the heater grid, however this is a not an issue as the thermal mass of the mirror does eventually melt any ice in these areas. Just like your back defogger heating grid it does not cover the entire window, but eventually the heat moves to those areas over time.

Thanks for linking to the video.

Since the pattern of frost at the edges is something I have seen before. and only affects one mirror, the only issue that comes to mind is that the heating lines behind are not well distributed (assuming that's how it works). If the lines are in a parallel parallel circuit configuration, then perhaps the one(s) by the frosty edges aren't working.

You said that the heating was detectable by touch, and the only explanation I can think of for me not feeling it is that, out in frigid temperatures, the equilibrium temperature of the heated mirror is much colder than within a heated garage in summer.

So now I'm disappointed again?
 

I have a 2016 EX-USDM.
Coincidentally, got a hit of winter weather right now. I have to say, I don't notice the side mirrors doing much of anything even with the rear defroster on. So I'm now assuming I don't have heated side mirrors.

Too bad, that's a nice feature, for anyone and everyone. Honda should make it standard.

Seems weird that Honda would invest so much into a "Safety Suite" of features, for almost all trim levels, but then NOT provide something as essential as defrost for side mirrors.

I turned them on and felt the mirror. Warm.

Canadian models get heated mirrors and seats.

I don't have heated seats on my 2014 Sport...

I manually added heated mirrors and led winkers from an EX-L CVT to my EX 6MT USDM. Mirrors activate with the rear defroster switch.

https://cimg9.ibsrv.net/gimg/www.fit...9e0ac1a156.jpg
Each mirror is ~7.8 ohms resistance. In cold weather they ohm out around 5.9 ohms. In a parallel circuit both mirrors will draw about ~4 amps. As the grids heat up the resistance rises and thus the current goes down. That's why its imperative to connect the mirror circuit to the rear defroster relay that time limits the grids. While low current, too much heat can shorten the life of the grids.
https://cimg7.ibsrv.net/gimg/www.fit...8727b0113b.jpg
driver side mirror
https://cimg8.ibsrv.net/gimg/www.fit...8f62d45b50.jpg
Heating grid connectors
https://cimg6.ibsrv.net/gimg/www.fit...f28f1aeb30.jpg
You must peel back the wire loom and splice the wire into the thick GREEN wire. The purple wire is hot and runs back to the 30A fuse underneath the driver side kick panel.
https://cimg5.ibsrv.net/gimg/www.fit...6ffc634e5a.jpg
With defrost switch on, the rear defroster relay energizes and completes the circuit to the rear grid, thus sending 12 volts to the red wire I tapped in with.
https://cimg3.ibsrv.net/gimg/www.fit...5ee419353a.jpg
routing power wires through pivot joint
https://cimg1.ibsrv.net/gimg/www.fit...c8dc245f6c.jpg
passenger mirror skull removed
https://cimg0.ibsrv.net/gimg/www.fit...2fc7b1c898.jpg
power wires 18AWG
https://cimg7.ibsrv.net/gimg/www.fit...d96559c3c1.jpg
completed heated mirror assembly passenger
https://cimg6.ibsrv.net/gimg/www.fit...d28357b923.jpg
Rear defroster relay location
https://cimg3.ibsrv.net/gimg/www.fit...7755fa987c.jpg
passenger LED & heated mirror wiring 01
https://cimg2.ibsrv.net/gimg/www.fit...7540bcbfbe.jpg
LED winker bench test
https://cimg1.ibsrv.net/gimg/www.fit...19d0e1b4e8.jpg
driver side LED winker complete

I use the defrost in the rain too. It keeps the side mirrors dry.

@Fitchet: Default heated mirrors might country-specific so that they don't get added in countries in which large areas don't experience frost on the mirrors. Perhaps they don't treat rear defrost as such a "contingent" feature because people breathing inside the car are likely to fog up the rear even in warm external temperatures.

@Action Jackson: Thanks for the confirmation that you feel the warmth. Were you indoors? I will try again to detect the warmth, but first try to find an indoor location. As I posted above, however, the issue seems to be persistent lack of edge coverage on one mirror rather than lack of heating.

@Frenzal: I don't have heated seats either. My Fit model is 2013 LX. I think it might not be a great idea for males.

@Bassguitarist1985: Thanks for all the pictures. I don't think I'll be doing it myself. Assuming that there are at least a handful of heating lines per mirror, the photos tell me that there isn't an individual wire for each heating line. If some of the lines aren't working, therefore, it isn't the result of the replacement of interior electrical systems after my car was flooded. It's likely that the entire mirror can be replaced. Probably an hour or two of a professional's time at a Honda garage (at over $100/hour in Canada).

@CommanderSlug: Thanks for the information that mirrors can be useful even in warm climates (keeping the mirrors dry when it rains).

Here is another shot of the persistent frost on the bottom and right edges. Again, only on the driver side mirror.


https://cimg0.ibsrv.net/gimg/www.fit...a6799a31e.jpeg