[thread resurrection - yes, I know there are several competing threads on Mud about installing dash cams and radar detectors, about using MirrorTaps (branded, generic or home made) for said radar detectors and dash cams, etc. I’m appending here, rather than starting a new thread. Yes, I know that many run their power wires down the A pillar to piggyback fuses, etc., but some of us just like to wire directly to the mirror area power and be done with it…this is for them.]
I just went through this the other morning and have a few small insights to add, with some photos that others may find helpful.
My LC200 is a 2018 with Toyota Safety Sense (radar adaptive cruise control, pre collision, lane departure warning, etc.). I had a 2009 that didn’t have this stuff, but I never hardwired anything on that truck, so I don’t know if the mirror setup is the same.
The plastic cover over the wires / guts above the mirror is two pieces, with generous cutouts for the mirror stem - a large piece (shaped vaguely like a really fat letter U), and a smaller rectangular insert / cap piece that is on the uppermost part of the cover. The second piece closes the top of the U to fully encircle the mirror stem. I believe this may be the same on some models of the Highlander as well, as I got some access information from a Highlander video on YT.
[photo is upside down vs. reality]
To remove the cover pieces, first place your fingers / thumbs on the tops of the U and push the entire cover assembly down, parallel along the inside surface of the windshield, towards the dash. It will pop off of its prongs after about 1/4”-1/2” of travel and will then flop around. You’ll be able to move it around, but both pieces of plastic cover will still be attached to each other, and they will still encircle the mirror stem.
It’s possible to install the mirror taps and cord around the (now disconnected) cover, even though it’s still encircling the mirror stem, but it’s probably easier to separate and remove the pieces for full access. This is risky (the first time), as you can’t see how the pieces are connected, and you might otherwise risk snapping off the thin plastic tabs…but here’s the trick: to separate the two pieces, pop the small cap piece out of the jaws of the U by pulling towards you on the topmost edge of the cap piece: pull that topmost edge of the cap perpendicular to the surface of the window - down and back, towards the center coolbox / console. Once those two clips (yellow circles) are released, slide the cap up and away from the U - the fingers (orange ovals) will come out of their slots, and the two cover pieces will separate and come away from the mirror stem.
In terms of electrical connections, I couldn’t find my multimeter, so I just randomly tried some “standard” color combinations that would have seemed to make sense, across the three connectors circled below. That’s not a good strategy. I ended up lighting up the dash a few times, throwing a bunch of error messages regarding the safety sense systems, etc. I went back and found a photo where someone (sorry - can’t recall where, so can’t give credit) had found that the black and tan wires on the right hand white connector gave switched power and ground (respectively), so I tried that and it worked like a charm. Black wire on the bottom right was power, tan wire on the top right was ground.
Reassembly of the cover pieces is just the reverse of removal, so that’s (hopefully) easy. There’s plenty of room around the mirror stem to get the power tap cable out from behind the cover, so no problems there.
I did run into a problem with the length of the power tap, however. I had (I think) a 10” MirrorTap left over from my last BMW, which was more than long enough for that vehicle. On the LC200, however, I mount my dash cam to the bare glass, which starts a bit further outboard vs. the BMWs due to the field of black dots on the inside of LC the windshield at the top center. The cam positioning is more in line with the driver’s line of sight, rather than the centerline of the vehicle.
The existing 10” power tap cord I had just wired in wouldn’t reach, and new 15” and 20” MirrorTap branded cables are $44 each, so I ended up purchasing two sets of 10” DC plug extension cords through Amazon before getting the correct one. The correct one for my MirrorTap cable and Blackvue dash cam has a 3.5mm x 1.35mm DC power plug, with a matching female receptacle on the other end. Once I had the correct extension, everything worked as expected. I zip tied the extension to the mirror stem, which will (hopefully) keep the tap from getting pulled out of the connector.
Anyway, hope this is helpful.