GENTEX GENK40A Auto Dimming Rear View Mirror

It was incredibly easy to install -- took me about an hour, and most of that time was spent testing the car's wiring harness to find constant-12V, switched-12V, and ground wires to tap into. (Get yourself a good Digital Volt-Ohm Meter if you don't already have one!)It does exactly what I wanted it to do -- no compass or temperature display, which I didn't want since I already have both of those built-in to my car. But it DOES have the Homelink buttons so I don't have to carry around a separate garage-door opener anymore (yay!). The Homelink setup-instructions are pretty clear, too -- you'll need your current garage-door opener, and depending on the type of garage-door opener you have, you might need a ladder to climb up and press a "train" button on the garage-door motor itself. (Having a second person help you with this is not a bad idea -- he/she can press the "train" button while you're in the car operating the Homelink button you're programming. Took me all of 2 minutes to train the Homelink buttons to work with my garage door with the help of my girlfriend. Just make sure you're parked in a place where the door(s) won't come down on your car accidentally while you're training the Homelink button(s). And, supposedly, if you have the right system, you can train one of your unused Homelink buttons (there are three of them) to turn on-and-off lights inside the house! (My system doesn't do this, so I can't verify that personally.)The auto-dimming feature works *wonderfully*. No more having to flip my mirror manually -- this thing auto-adjusts the dimming depending on how bright the lights are behind you (goes from a little dimming to a LOT of dimming as the person gets closer to you), and it does so quite quickly so there's never a problem with glare ever.I highly recommend buying this mirror if you want an auto-dimming mirror that has the Homelink buttons on it, but you don't want the temperature or compass displayed in the upper-right corner of the mirror.

I'd give this 5 stars if the "after market cable" provided was labeled (or wiring instructions were included) because this mirror/homelink product is excellent.It's in and working as advertised. That's the good news. The bad news is the installation was a lot longer and harder than the "1 hour" other reviewers indicated. I'm a biomedical engineer who actually installed X-Ray machines in hospitals so I know my way around a tool box. Here are some installation hints that may help future buyers install this excellent product:1. The cable came with 2 different power wires (at least I think they were both power). One wire was solid black and the other was black with a white stripe and the ground wire with a spade lug. I reached out the seller and asked how to connect the 2 power wires. They couldn't remember. I did much research and the consensus of the group was to connect the power wire a ignition switched power source. I connected both wires to a switched power source. I turned on the ignition (with fire extinguisher in my hand) and the Mirror powered up and programmed perfectly. It continued to work after switching the ignition off and on. Yeah!2. The other tip is: figure out what type of fuses your car uses and buy an "add a fuse" kit from Amazon for your fuse type. My Hyundai uses micro2 fuses so I ordered the correct "add a fuse kit" (pictured below). With THAT said, my Hyundai had tons of "spare" fuses and several fuses for features not included in my car (like power sun roof) but almost all of them were 24 hour power or hot with the ignition switch off. Only 3 unused fuse positions were switched power.3. Finally a note about the "add a fuse"; be sure to check which leg is hot in your car's used box and which leg on the "add a fuse" if connected to your output wire. Otherwise you will end up not going through your "add a fuse" fuse but connecting your power wire directly to the fuse block. Not good.GENTEX GENK40A Auto Dimming Rear View Mirror

I had hoped to have this style mirror for the Prius Prime that I just purchased, but it wasn't an option for the XLE (middle) model that I ended up buying. Dealership purchase and install of this style mirror would have been $1,000 or so, so I found the GENK40A with the hope it would fit. Turns out the installation was relatively straight-forward and it works absolutely perfectly. To install, I removed the ceiling cover and stock rearview mirror, installed the new mirror (easy). Importantly, I needed to carve out part of the mirror cover with a Dremel tool in to allow the GENK40A to have enough upward movement so that I had appropriate line-of-sight out the back window. (If you're really tall, it might be a problem to get enough vertical clearance.) I then ran the GENK40A wire along the left side moulding (taking care to stay behind the airbag), and down to the fusebox under the left-side dashboard, where I connected the wires to the fuse for the 12V outlet. Getting the HomeLink to connect with my fairly old garage door opener took a number of tries, but it eventually worked. Couldn't be happier!