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Compass/Temp/Auto dim mirror swap (detailed with lots-o-pics)

157024 Views 195 Replies 71 Participants Last post by  N8N
I saw this mod in someone elses post but the write up was vague and lacked the wiring diagram so I decided to do my own after finishing up my mirror swap.

The particular mirror you'll need to locate came on multiple GM models in different versions but the one your looking for is the 7 pin model most commonly found from 1995-2002 in Chevy and GMC trucks and full size SUV's also known as Gentex model number GNTX-177.

Besides the mirror itself, you'll need the 7 pin mirror connector w/ a small pigtail of wire, the ambient temperature sensor and sensor connector w/ a small pigtail of wire shown here;


The compass is part of the mirror itself but the temperature sensor is located on the front core support below the horn or on some of the newer models, right by the drivers side headlight. make sure to get at least 4-6" of pigtail for each connector to make wiring easier.

Once you've got those 4 items you need to decide how involved you want to make this and how much you care about your wiring job. Personally I overdo everything when it comes to wiring and this write up reflects that but there are quicker, cheaper and less involved ways to accomplish the same goal, i.e. using butt splices instead of solder joints and heat shrink, using split loom instead of braided expandable tubing etc.

You'll need the following items before you start but like I said, your list may differ from mine depending on what route you choose to wire your mirror in.

Materials
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10ft - 20 gauge red stranded wire (power)
10ft - 20 gauge black stranded wire (ground)
10ft - 20 gauge black stranded wire (sensor ground)
10ft - 20 gauge green stranded wire (sensor power)
soldering iron (if soldering)
solder (or butt splices)
1/8", 1/4", 3/8" heat shrink tubing (or electrical tape)
PET braided expandable tubing (or split loom)
sheet metal screws
cable clamps in 1/4" or 3/8"
zip ties
electric drill
drill bit - 1 size smaller than sheet metal screws your using
sharpie (silver/black)
12v circuit tester
ring clamp - for ground wire
razor knife
wiring pliers
phillips screwdriver
torx - for mirror set screw

To start off with decide where you want to mount the temperature sensor, it will determine the length of your wiring run from the sensor to the mirror. You can put it anywhere there isn't a lot of heat and out of direct sunlight, just remember the further away from ambient heat (engine bay, radiator) you can place the sensor the more accurate it will be.

Next, you need to decide on which side of the windshield your going to run the power/ground/sensor wires to the mirror. Either side of your Jeep will work since there is switched power and ground on both sides of the dash, its more a matter of personal preference than anything.

Once you have your basic layout set its time to start on the mirror wiring. Start by stripping off the old covering so your left with a plug that and 7 wires;


Wiring for this particular mirror is as follows;


Your only going to be using wires 1, 2, 6 and 7 so remove wires 3, 4 and 5 from the connector. To de-pin the unused wires simply push down the retainer tab and pull the wire and pin out of the connector;


To start off, strip 1/2" of the insulation from the 4 remaining mirror plug wires and your 4 sections of new red/black/green wire then take your new lengths of wire and begin to wrap the stripped ends around each of the wires on the mirror connector like this;


Next solder the 4 lengths of wire together and then heat shrink them. Mark the end of either the black ground wire or the black wire from the temperature sensor so once its covered by the sleeving you can identify it and not mix it up with the other black wire when connecting everything, a silver sharpie works great for this step or use electrical tape etc;


Next, take a short section of the braided expandable tubing and slide it over all 4 wires. Its a pain to do but it leaves the harness seamless and very strong since any strain on the wires tightens up the sleeve and strengthens it. Once thats done slide a 1" or so piece of 3/8" heat shrink tubing over all 4 wires and the braided sleeving, close to the mirror connector but leaving a small bit of the wires sticking out of the braided sleeve, then shrink it down. Repeat this step for the end that goes behind the dash;


Locate the 2 wires (black and green) for the temperature sensor and crimp one male and one female insulated spade connector to each of them. This step isn't that important and they can be connected by any means you choose, I used polarized spades so they can't be connected wrong without cutting the ends off and re-crimping, doing so idiot proofs the harness for anyone working on the Jeep besides myself.

Next step is to build the wiring harness for the temperature sensor. On mine I made this part of the wiring harness seperate from the mirror harness so if I have to remove either of the harnesses in the future I don't have to tear everything apart.

Start by sliding a 1" long piece of 1/8" heat shrink over both of the wires on your sensor pigtail up to the plug itself and shrink it down;


Now take your 2 sections of new wire and strip 1/2" from each of the ends. Repeat this step on the 2 wires on your sensor pigtail then twist the 2 like colored wires together like you did with the harness for the mirror.

Solder the 2 joints, let it cool, then slide a 1" long piece of 1/16" heat shrink over your solder joints and shrink them;


Next measure out a piece of braided expandable tubing thats approx. 6" shorter than the length of your wiring harness and slide it over the wires leaving a 1/2" +/- gap at the end by the sensor plug. Slide a 1" long piece of 3/8" heat shrink over the sleeve to the end where the plug is. Make sure to cover the end of the braided sleeving and the wires protruding from the sleeve keeping it close as possible to the plug itself then shrink it over the sleeve and wires. Slide another piece of 3/8" heat shrink over the end with the bare green and black wire and the sleeve and shrink it down. This keeps the braided tubing from unraveling or fraying. Now crimp 1 male and 1 female insulated spade connector to each of the wires, doesn't matter which as long as they match the harness for the mirror Male to Female on each wire. Your end harness will look something like this;


Next, remove your factory Jeep mirror from the windshield. You'll need a torx to loosen the screw but I'm not sure which size since mine simply slid off even with the screw tightened up all the way. Slide your new mirror onto your factory Jeep mount and tighten it up till its snug.

Plug your mirror wiring harness connector into the back of the now mounted mirror then route it along the windshield frame and down behind the dash making sure to leave at least 2-3" slack at the mirror end for adjustment without putting strain on the wires. On mine I drilled some small holes and used 3/8" black plastic clamps and black metal screws to attach the cable to the windshield frame, running along the top towards the drivers side, then down the windshield pillar behind my flashlight mount and into the dash.

Another way to route the wire from the mirror to the dash is inside the windshield frame by drilling a hole above the mirror shown Here.

Lastly, if you have a newer wrangler you can just drill a small hole and run the wiring inside of your windshield trim;


Now find a good ground and using a ring connector ground the unmarked black wire to the body of the Jeep. I used the factory dash ground directly below the drivers side speaker;


Now break out your trusty circuit tester and find a switched 12v + power supply to hook up your mirror (+) to, make sure to use a 5amp inline fuse between your mirror (+) and whatever you tap into. On my setup I hooked the (+) red power wire of the mirror harness to the switched (+) I ran to my KC lights switch.


Once you have both the power and ground connected you can turn your ignition on and check to make sure your mirror powers up. If so, the compass and temperature gauge LCD window should power up and show a bunch of random characters. If the initial power up phase occurs the next thing you'll see is going to be "C" or "CAL" when you click the compass button and "OC" when you click the temperature button. Not to worry, the compass has to be calibrated and the temperature sensor will display "OC" for "open circuit" because you haven't connected the actual sensor yet. If the mirror powers up correctly then move onto the next step, if not you screwed up and need to check your connections or worse case you got a bad mirror.

Next step is to feed the sensor harness you built earlier through the firewall to the sensor mounting location you decided on. Slice a small hole in one of the firewall grommets and feed the wire through to whatever mounting point you chose, making sure you have a few feet of slack to route the wire around the engine bay.


Route your sensor harness along whatever path is shortest and most conventient then secure the harness with zip ties making sure it away from moving or sharp parts and then mount your temperature sensor. For this install I'm placing the sensor under the front left fender on the brace as there is already an existing hole that a 3/8" bolts fits through perfectly.


Once you have the sensor mounted up and the wiring ran and secured, power up the mirror by turning the ignition to the "Accessory" position and verify that your temperature function of the mirror reads an actual temperature and compare its reading to a thermometer. If the readout is horribly wrong or locked on 50 degrees, contact your GM dealer for a new one (p/n 15029274, $23) or return to the junkyard for a replacement, better yet hunt around and grab a spare when your there the first time just in case. Once thats done your ready to move on to setting and calibrating your new mirrors features.

Temperature display adjustment
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To change the mirror temperature display between farenheit and celcius simply push and hold the "Temp" button until it flashes "f" or "c" on the side of the lcd, then press it again to change display modes. The mirror will switch back to temperature mode and now display in celcius or farenheit. The mirror also has a built in warning that will flash "ICE" every 6 seconds to alert of potential hazardous conditions when the temperature drops to 36f or 2c.

Auto-Dimming Switch Function
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Hold "Temp" switch for 15 seconds to disable auto dimming and the green LED will go off, Repeat to enable auto dimming and the green led will come on.

Compass Variance
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The mirror compass allows you to set the compass variance depending upon your location in North America. The mirror is set in zone 8 upon leaving the factory. It will be necessary to adjust the compass to compensate for compass variance if you live outside zone eight. Under certain circumstances, such a long distance cross-country trip, it will be necessary to adjust for compass variance. If you do not adjust your compass to account for compass variance, your compass can give false readings. To adjust for compass variance, do the following:

1. Find your current location on the map below.
2. Press and hold the COMP button for three seconds until a zone number appears in the display.
3. Press the COMP button on the bottom of the mirror until the new zone number appears in the display. After you stop pressing the button in, the display will show a compass direction within a few seconds.

US and Canadian variances;

Worldwide variances;


Compass calibration
-------------------------------
Once the mirror is connected and powered up the compass display will read "C" or "CAL" because a long term loss of power allows the mirror to lose its setting of where north is and needs to be re-calibrated. If your mirror powers up and displays a heading, chances are its wrong and you need to force the mirror into calibration mode. To do this hold the "comp" button down for approximately 6-10 seconds or until it reads "C" or "CAL" then proceed to the next step.

If your compass is displaying "C" or "CAL", simply drive in a tight circle (in a parking lot for example) under five miles an hour until a compass heading is displayed. Typically this should take less than three complete turns. If this doesn't work, drive normally and over the course of your route a heading should display.
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I have the factory com./temp.mirror, but like the idea of adding the home link. Is the wiring mod. the same for the Gentex 341 if I use the factory harness that I already have?
 

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resurrecting this old thread. Thanks for the write-up!

The wiring harness you mentioned is discontinued, of course.
I ordered this one: 68270613AA. No idea if it's going to work. Can't tell from the pic, but some evidence points to this working with the Gentex/Mopar connectors.

Would you happen to have any photos of the harness? Particularly the female end that connect to the plug in the dash? I have the plug and verified the temp sensor is connected. If nothing else, if I could get the plug with crimped pigtails, that would work. Or, if the part number of the plug itself is known, I could probably find one and crimp my own wires into it.
 

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When I grabbed mine from an early 00's Tahoe I grabbed the wire harness from the mirror and traced it by cutting into the roof liner. I ended up with 4 or 5 ft if I remember. I then went to the front and grabbed the harness from the sensor and traced it up to the firewall where I cut. Maybe another 5 ft. Once home I just soldered them together after I routed thru the windshield frame. Only 4 wires are used.
 

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I recently did this on my '05 too. I found a '00ish Suburban. Got the mirror, pulled the headliner down & pulled the harness all the way to the bottom of the A pillar & cut it there. That gave me just enough length to reach the factory mirror harness under the dash cover (so no need for the discontinued mirror pigtail). I could not source a connector to match the dash one so hard wired the 2 together matching the wires as directed previously. Having my '05 wired from the dash to behind the grilled worked perfectly. I also grabbed the GM sensor located in front of the radiator & its connector/wiring if needed but I was able to source a now discontinued ambient air temp sensor to mount in the factory location. I find the temp readings to be very accurate using the OEM sensor.

So now having the extra GM sensor I used it to add an interior sensor. Now with the flip of a switch I can get either outside or interior temperatures.
 

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.,, I can get either outside or interior temperatures.
That's awesome 😉

I could have gone with the 177 like that. Would have saved me tons of dough. But the 177 doesn't have a map light. And I went a little OCD about having Comp AND Temp AND a map light.

And now I'm OCD'ing about that stupid connector. If I have to hardwire I guess I'll have to but it's going to bug me for a while. Fortunately, along with OCD I have a short attention span.
 

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I thought about finding one with map lights but had been "thinking about" at least getting the temp feature for probably 6 or 7 years & have follow this thread. Then I was walking through a pull your part looking for a part for the 4Runner when I spotted the Suburban. I figured it was then or never so got what I needed.

We rarely drive the Jeep at night so who really needs map lights anyway? In fact this mirror had the auto dimming feature which I got working but have never even used that. I do like having the temp display (being in the desert, you know) so worth it.
 

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I know this is an old thread but I had a question that I somehow have never seen mentioned.

I'm trying to put a 177 into my 2000 wrangler but I've run into 2 problems.

1. The OEM Jeep mount on the windshield is too narrow for the 177 mirror, are other people swapping the glued on mount with the GM one?

2. The big thing is that the mirror seems too wide and it hits my sun visors. Has anyone solved this problem?

Thanks
 

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I know this is an old thread but I had a question that I somehow have never seen mentioned.

I'm trying to put a 177 into my 2000 wrangler but I've run into 2 problems.

1. The OEM Jeep mount on the windshield is too narrow for the 177 mirror, are other people swapping the glued on mount with the GM one?

2. The big thing is that the mirror seems too wide and it hits my sun visors. Has anyone solved this problem?

Thanks
I'd have to check what i did with the button on the mirror I added to my 97. I don't know if I got it to fit with just using a longer screw. For the sun visors, I picked the stitching, trimmed the card in the visors so they would clear the mirrors, then also trimmed the PVC outer and hand stitched the trim around the new shape, trimming the excess. I'll go take pics of the visors and see if I can figure out what I did with the mount.

Edit:

I used the original button. The screw I used is the only one I could find at the time with the same thread. It is a hex flange head and pictured balanced on the air vent for an idea of size. It's actually a perfect size as the screw bottoms out on the mirror just as it secures the mirror to the button.

The drivers side shade wasn't trimmed back as much as I did with the passenger side and only just clears the mirror. It would be better if trimmed back more, but it clears, so I'm in no rush to do it.
 

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I know this is an old thread but I had a question that I somehow have never seen mentioned.

I'm trying to put a 177 into my 2000 wrangler but I've run into 2 problems.

1. The OEM Jeep mount on the windshield is too narrow for the 177 mirror, are other people swapping the glued on mount with the GM one?

2. The big thing is that the mirror seems too wide and it hits my sun visors. Has anyone solved this problem?

Thanks
I'd have to check what i did with the button on the mirror I added to my 97. I don't know if I got it to fit with just using a longer screw. For the sun visors, I picked the stitching, trimmed the card in the visors so they would clear the mirrors, then also trimmed the PVC outer and hand stitched the trim around the new shape, trimming the excess. I'll go take pics of the visors and see if I can figure out what I did with the mount.

Edit:

I used the original button. The screw I used is the only one I could find at the time with the same thread. It is a hex flange head and pictured balanced on the air vent for an idea of size. It's actually a perfect size as the screw bottoms out on the mirror just as it secures the mirror to the button.

The drivers side shade wasn't trimmed back as much as I did with the passenger side and only just clears the mirror. It would be better if trimmed back more, but it clears, so I'm in no rush to do it.
Wow awesome reply, thanks. The stitching you did looks great. I'd be nervous to try the same, but it might be the only way.

The problem I have with the original foot isn't the screw, it's that my original foot is narrower, side to side, than the gentex foot. So as soon try to tighten the screw, the sides of the mount have nothing to grab and just pop right off. I have the gentex foot that came with the mirror but it has glad still glued to the back of it, so I'm not sure it's useful, maybe I'll just buy a new one.

Thanks again! I'll sit and stare at the visors and see if I can build up some courage and if I can make it look factory after trimming.
 

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I am using the original button on my TJ with my Gentex mirror. I got my mirror brand new off ebay for £35, and it is a Mopar part (I think it was listed as for a Liberty). It's very loose on the button until the last moment when it locks in place. I actually had it for a few years before my heater core needed replacing, which was the perfect opportunity to tidy up some old wiring and add the new wires for the mirror. I should take a pic or two to show how I routed the wires, but it's dark out now so it will have to wait. Maybe I should unscrew the mirror again and see if I did anything with the button to make it fit. I know i never removed the button from the windshield, and I think the Gentex mount I have is in glove box, to be used if the screen needs replacing in future.
 

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I'll try it on the Jeep button again. Before, it was loose enough that if one side hooked on the Jeep button the other side would just fall off. I'll try to center it better and hope that there's just enough on all sides to grab so that it can stay on once tight. Thanks again.
 

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Forgot to have another look at my button for you. I've recently started back at work and it's hard going after seven months on furlough. To add to that I have a screech under acceleration that I'm trying to narrow down, so I'm more than a little distracted.



I don't know if the stock button has a dimple in it where the screw sits or whether I added one where the screw centers. I think the longer screw I used was crucial to it working with the stock button though.I'll try and look at it again over the weekend if I can remember.
 

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Returning to this old thread. I was actually the guy a few pages back (see post #130) who figured out what connector to order for the mirror to make a wiring harness. I now have another Jeep and would like to install my old mirror in it but knowing what I know now would like to do a neater job this time. Has anyone figured out what to order for the connector down on the passenger side kick panel of a late model XJ? I'm thinking I could hook the mirror into the connector for the factory overhead console, which I don't have, and have a really neat installation. My old Jeep I was never happy with because the mirror would reset periodically, I was tapping power off the stereo, don't know if that was the problem or not.
 
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