How-to install a Gentex 177 compass mirror in a TJ / LJ

MountaineerTom

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Almost 2 years ago, I got a Gentex 177 Compass/Temperature/Auto-dimming mirror from an early 2000's Chevrolet Silverado in a salvage yard and installed it in my 2006 LJ. Mine didn't come with the harness under the defrost panel on the dash like some TJ/LJ's do, so it wasn't a plug-and-play job, but it wasn't that hard to do either. I got the mirror with connector and pigtail, sensor and connector with pigtail for about $15 if I remember correctly. I made my own harness and routed it behind the passengers side A-pillar and behind the trim at the top of the windshield. Had to make a little notch in the windshield trim panel for the harness to come through without getting pinched. I tapped into the fuse block for switched power, tapped into the reverse light so it would un-dim for a clearer image when in reverse, and run 2 wires up to the drivers side bottom part of the grill for the temp sensor (where the OEM sensor would be). Like every other vehicle I've owned or currently own, it will read high temps when sitting still for a bit.

The pin out of the connector on the mirror is as follows. I can't guarantee all are like this, but mine was.

Gentex 177 Mirror GM wiring
Pin 1 - Red/Pink, 12 volt switched power
Pin 2 - Black, Ground
Pin 3 - Light Green, Backup lights for auto dimming. Connect to violet with black tracer on gear range selector on transmission. I came across that somewhere on another forum, but what I did was ran it through the interior following factory harness on drivers side towards drivers rear taillight, tapped into white with green tracer which feeds the purple with black tracer to the reverse lights.
Pin 4 - Gray, Outside mirror dimming (not used on Jeep)
Pin 5 - Pink, Outside mirror dimming (not used on Jeep)
Pin 6 - Green/White, Temp probe
Pin 7 - Black/White, Temp probe



mirror.JPG harness1.JPG harness2.JPG harness3.JPG autodim1.JPG
 
Thanks. I looked around for one with map lights but couldn't find one. I also considered getting the OEM harness's and trying to go the plug-and-play route, but after looking over my Jeep, it didn't even have the end to connect the harness to. I looked all through that thing and couldn't find anything but a small connector that I think was is for the Subwoofer option.
 
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Another great write up! I actually installed my GNTX 177 mirror last week. I had no desire for map lights, mine came out of an early 00s Tahoe. Maybe I need to look again but I did nothing with the light green wire and my mirror auto dims with only pwr, ground, and the two temp probe wires.

IMG_3102[1].JPG
C301CC2B-2BD4-4E5A-8032-2A8FD6A5BDAF.jpeg
 
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From what I understood, the light green wire hooked up to the reverse light wiring makes the mirror UN-dim when you put it in reverse so you can see clearer. Them dims again when you go out of reverse. At least that’s what mine does.
 
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From what I understood, the light green wire hooked up to the reverse light wiring makes the mirror UN-dim when you put it in reverse so you can see clearer. Them dims again when you go out of reverse. At least that’s what mine does.

Ah gotcha. A feature I don't need then. Still good to know!
 
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Yeah. I almost didn’t hook it up, but decided to while I was wiring stuff.
 
Another great write up! I actually installed my GNTX 177 mirror last week. I had no desire for map lights, mine came out of an early 00s Tahoe. Maybe I need to look again but I did nothing with the light green wire and my mirror auto dims with only pwr, ground, and the two temp probe wires.

View attachment 62350View attachment 62355

Any tips on running the wire through the windshield frame like it appears you did? I currently have the wires for my mirror showing and looking for a setup similar to yours.
 
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Any tips on running the wire through the windshield frame like it appears you did? I currently have the wires for my mirror showing and looking for a setup similar to yours.

I drilled a 3/8" hole center of the windshield frame, just below the footmans loop. Drilled another 3/8" hole in the A-frame (see second picture, hole just above dash), and literally just pushed the wires thru. It took maybe 30 minutes to finally get them all thru, I fashioned a hook out of some baling wire which also helped. Then hooked them up to the fuse panel behind the glovebox.
 
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How are you guys getting the metal bracket to stick to the windshield? I got lucky and my Lj came with the mirror but I am always having to reapply the damn metal piece to the windshield. I am not doing anything crazy or bouncing hard it just comes off. I had it done by an auto glass place but 2 years later it popped off. That way better then when I did it myself, sorry for the rant. Just wanted to see if you guys know something I don't.
 
How are you guys getting the metal bracket to stick to the windshield? I got lucky and my Lj came with the mirror but I am always having to reapply the damn metal piece to the windshield. I am not doing anything crazy or bouncing hard it just comes off. I had it done by an auto glass place but 2 years later it popped off. That way better then when I did it myself, sorry for the rant. Just wanted to see if you guys know something I don't.

I believe they sell an adhesive meant just for this at auto part stores.
 
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Yes, they do sell specific adhesive for the mirror mount. I don't know what makes it specific, but the auto parts stores sell them.

Clean the area really good, and then clean it again. I used Naptha (lighter fluid) to clean the area. Then don't use to much of the adhesive. I read a thread somewhere where an individual kept having theirs falling off. Some one suggesting using less adhesive. They tried that and had success.
 
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I'm about to do this but was just curious if anyone knew what year TJs started having mirrors like this with the factory wiring tucked under the defrost panel? I didn't look for wiring in mine yet and doubt I have it in a 98 but I did look in my factory service manual and doesn't list it anywhere.. wiring diagrams or anything related to removing/installing the rear view mirror.
 
I'm about to do this but was just curious if anyone knew what year TJs started having mirrors like this with the factory wiring tucked under the defrost panel? I didn't look for wiring in mine yet and doubt I have it in a 98 but I did look in my factory service manual and doesn't list it anywhere.. wiring diagrams or anything related to removing/installing the rear view mirror.


I'm sorry @jeepins , I don't know when they started.
 
I know the wiring for this is pretty straightforward but just makes me wonder how Jeep wired the harness/plug in the ones that had it. I too have a 98 Sport.
 
Hijacking this older thread

I just did this mod but my display is really dim. The manual I have only shows how to turn on and off the auto dimmer. Does anyone know if there is an display intensity or brightness adjustment?
I might have gotten a bad mirror


Thank you
 
I don't know of a way to manually adjust the brightness. I don't recall ever hearing about it.

It should adjust itself depending on if it's day or night. I think that's what the sensor on the forward side of the mirror is for. The one near the buttons is for sensing light behind you and auto dimming the mirror.

You might try covering the sensor on the front and see if the display changes. You can also test the auto dimming by shining a flashlight at the sensor.
 
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