Auto Dimming Mirror Install

Heya! This modification is for speed3's that didn't come with the auto dimming rear view mirror from factory. My model is a 2007 Mazdaspeed3 Sport, and I've done a different modification before for the pop-up screen; a lot of harness wiring diagram's will be borrowed from that post. The driving reason of me doing this was because I wanted to change my manual rear view mirror due to some weird gunk or some sort of deterioration happening behind the glass which I can't clean.


So first off, I'm not too knowledgeable about rear view mirror's but I do know that I prefer the look of the Gentex mirrors, and I found one from the junkyard from an Infiniti G37. It's one of the more special mirrors (that I've seen) that has lcd compass behind the actual mirror. When it's on, it's seamless. Where as there are many of the other variant where there is a black hole cut out of the reflective mirror. The specific model is the ZTVHL3:


Here's the pin out for this mirror that I've figured out from some posts online:
Red - Battery +12v
Black - Ground
Orange - Accessory +12v
White - Reverse +12v

The purpose for the reverse switch is for the mirror to turn off the dimming when you enter reverse. I assume other Gentex mirrors have the same pin out, but I'm not too sure. I'll be doing this again but for our 2014 CX-9 except it has just Auto-Dimming + Homelink.

You can find the Battery +12v and the Ground from the domelight. Getting the accessory and the reverse switch will require you to remove parts of the dash to get to.

(Ground isn't connected here as I had to extend all the wires to reach the domelight harness)

Reverse is taken from the cabin fuse box (located above the passenger foot well), the link for the pinout of the fuse box is attached via pdf and link, but some images of what you're looking for:


(Source: https://www.motor-talk.de/forum/aktion/Attachment.html?attachmentId=802208)
Then the last thing you need is Accessory, I've taken it from the head unit so you'll have to run a wire up the passenger A-pillar, you'll have to take apart the dash anyway to get the fuse box wire up the A-pillar aswell.

The diagram of the headunit is below, it's just tapping into the Yellow wire off of it.

(Source: https://pinoutguide.com/Car-Stereo-Mazda/Mazda_3_2004-2005_pinout.shtml)

To summarize the pinout:
M = mirror

M_Red (Batt 12v) = Red (from domelight)
M_Black (Ground) = Black (from domelight)
M_Orange (Acc) = Yellow (from headunit)
M_White (Rev) = Green/Black w/ Silver Dots (from cabin fusebox)

And when it's all done, you'll have yourself a nice autodimming mirror that'll work with your garage door opener!



Wish I took more photos of the dash taken apart, but honestly I couldn't be bothered since the wide angle lens wouldn't really do it much justice with how the wire's are run and I had my hands full. If you've ever taken apart the dash, it's very simple wire routing since there's already a harness going up the A pillar. Please consult the workshop manual on how to take apart the interior and the A-pillar if you haven't before. Especially the pillar because of the special clip at the top that you need to slide off.

Hope this serves to help someone! I found a bit of info about the mirrors confusing. Some are referred to as the Gentex-455 and 458? I have no clue, but I'm just glad I had a mirror who's wires were appropriately colored and the pinout on other Gentex mirrors would appear to be the same despite the different wire colors.