Gentex auto-dimming, HomeLink mirror install (Civic but applies to NA/NB Miata)
Nothing is worse than clipping an obnoxious garage-door remote control on the sun visor and in the case of the well equipped Honda Civic with remote start, it's inexplicable why HomeLink was omitted. NA and NB Miata owners have always been exempt for some reason as well.
Thankfully, Gentex mirrors with HomeLink remote controls are readily available for super cheap. I used to think they were in the $250+ price range but turns out, they're about $45 with wiring harness included. Besides being able to open the garage via the mirror's HomeLink feature, the Gentex's auto-dimming feature is worth its weight in gold. How many times has anything taller than you, which is everything, stopped right behind you with its headlights searing into your skull?
Nowadays, there's no excuse for not having one and after discovering my new car's lack of this basic necessity, I decided to remedy this problem. As I said, the Gentex can be had cheap on eBay and turns out, they're the preferred choice for many OEMs. In fact, the mirror I ordered is exactly the same as the one in my Mazda6 I'm sure I was charged a premium for. There are several models of Gentex mirrors and if you want one with the goofy compass, it'll cost more and you'll have to drive around in circles trying to calibrate it. Much easier to be a man and use your own primordial sense of direction anyway.
So, if you're on the fence in terms of cost, let me reiterate that this is genuinely a cheap mod that yields dividends. Here is the basic $45 kit as ordered: mirror and wiring harness.
http://i1194.photobucket.com/albums/...pstuq8qvtw.jpg
The mirror mount is a generic "V" shape that conforms to most manufacturer's tapered windshield slugs. While the Civic uses a Torx tightening screw, NA and NB Miatas use a release clip on top but the actual mount is a typical V-shaped windshield slug, hence the aftermarket Gentex will fit just fine. I don't have experience with NC and ND Miatas so I can't offer advice although I suspect they're the same.
Example of the Civic's and Miata's craptastik rear view mirror.
http://i1194.photobucket.com/albums/...psdav3pqoz.jpg
Yeah, pretty generic. It'll work.
http://i1194.photobucket.com/albums/...psbtv8ah3c.jpg
Typical windshield slug.
http://i1194.photobucket.com/albums/...ps7qity69r.jpg
Also included is the wiring cover with little tabs that snug into the headliner. If the length is too much, just cut it down with a hack saw.
http://i1194.photobucket.com/albums/...psjj8c7pbt.jpg
Of course, the mirror needs to be powered in two ways and that requires running power and ground to it. Since the mirror requires a 10-pin harness (included in the kit when purchased that way), one source of power is the dome light but since the harness calls for both a +12v switched (and for some reason) a +12 constant source, a wired connection will be required from the fuse box.
This is not a terribly difficult thing but will require accessing the A-pillar and running a wire through to the fuse box. Personally, I think the switched source could be eliminated so long as the mirror is getting constant power from the dome light but I figure the Gentex engineers have their reasons so I follow them. If you don't want to use a T-tap on the dome light wiring, just follow along and run the wiring through the A-pillar and down to the fuse box for both switched and constant power.
For the NA/NB Miata, just remove the A pillar via removing the sun visor mount and start pulling plastic. The A-pillar trim will pop right off. You'll see a way to fish the wiring through. For the Civic and ND Miata, there is a side-curtain airbag present which is no obstacle as long as you run your wiring behind the airbag assembly. I can't stress this enough. Make sure to run your wires behind the airbag. It's both prudent and necessary.
Here is a Civic A pillar. Notice the side-curtain airbag assembly (Whew! It's not Takata!):
http://i1194.photobucket.com/albums/...ps3jli3u1g.jpg
Now run the wiring behind it. It's just common sense really. If the wires are in front, the airbag can't protect you. If they're behind, they won't interfere during an accident. Use extra zip ties to run the mirror wiring past the airbag harness, not at its mounting point.
http://i1194.photobucket.com/albums/...psxjprozvj.jpg
Where applicable, always apply foam padding or other device to prevent wires from rattling. In this case, I just cut pieces of foam from a yoga mat and stuffed into any crevice I suspect wire rattling could happen.
http://i1194.photobucket.com/albums/...ps83rm9h6h.jpg
If you run the wiring harness down to the fuse box, make sure to have a couple of Add-A-Fuse type devices. In my case, I ran two: one for switched and one for constant power.
http://i1194.photobucket.com/albums/...ps2t8tubm3.jpg
Review: I've been driving around with my new Gentex setup for a couple weeks now and the garage door opener is indispensable! I love opening my garage door while I'm a block away. The auto dimming is super nice since I've had several opportunities to use it with maladjusted people behind me. The side view mirrors remain a little bright but the Gentex rear view works as advertised. Very comfortable.
Well that's it! Any questions, just post.
