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

161K views 195 replies 71 participants last post by  N8N 
#1 · (Edited)
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
--------------------------------------------------
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
------------------------------------------------
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
-----------------------------------------------
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
------------------------------------------
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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#2 ·
Temperature sensor addendum
-----------------------------------

After cruising the junk yards for mirror swap parts I decided to add this little addendum to my original write up regarding the temperature sensors.

I noticed after looking at certain vehicles and doing some research I found out that GM used 2 different types of temp sensors and 2 separate types of sensor plugs and the 2 different styles are not interchangeable regardless of what the dealer parts monkey says his computer shows.

In this image you'll notice 2 of the sensors are identical with the exception of the mounting brackets and 1 is completely different. The two that look the same are the same and will interchange with each other so if you need/want one style or the other your fine. The third style, "C" is not interchangeable due to the plug being different, but using that style plug from the get go allows you to use the newer and cheaper air temperature sensor. People on the various GM forums swear that the new style is more reliable and less prone to false readings but I used the older style, "A", in my setup and its dead on with the thermometers I have at home, as are the rest of the older style sensors I tested.


Notice in this picture the green plug in the center, "2". It is the only plug that fits the newer style temperature sensor "C" from the previous picture due to the seperating notch the arrow points to. This sensor can be used just fine and was most common in newer vehicles that had the temperature readout displayed on the climate control instead of the mirror. Also notice in the picture that the wire color and gauge on the connectors are different and vary slightly from green and black to green and yellow. From my tests as long as you connect green to green and black to whatever is the odd color your good to go.
 
#4 ·
Way to go. Excellent write-up. I personally don't need that mod but was just checking out my old stomping ground and having a look around. I've read plenty of write-ups and have done a few myself but yours is the best. :thumbsup: :cheers2:
Thanks! I spent a lot of time on it so its nice to hear its actually informative. :thumbsup:
 
#6 ·
I did it in a little less than 3 hrs start to finish but I spent a bunch of time figuring out the wiring, If I hadn't I could have done it in an hr or so. If you feel like doing it and have a problem just post up and myself or others will chime in and help you out. As long as you can measure wire and use a tester light your good to go.
 
#9 ·
Nice job on the wiring. This is a mod that's on my shortlist, however I want a mirror that also has Homelink buttons.

Another option for the inside wiring, for those of us who have older TJ's without the plastic trim, is to actually run it inside the windshield frame. Someone on here did it (Oman Jeep maybe?) and looked really good.

He drilled a small hole in the bottom of the frame, right above the mirror. With the windshield folded forward, the wire was able to be snaked through so it came out by the hinge.
 
#11 ·
Nice job on the wiring. This is a mod that's on my shortlist, however I want a mirror that also has Homelink buttons.

Another option for the inside wiring, for those of us who have older TJ's without the plastic trim, is to actually run it inside the windshield frame. Someone on here did it (Oman Jeep maybe?) and looked really good.

He drilled a small hole in the bottom of the frame, right above the mirror. With the windshield folded forward, the wire was able to be snaked through so it came out by the hinge.
I saw a bunch of the homelink ones in the yard and thought about swapping that in it but they wanted $80 for all the parts, most likely because they'd have to dig into the dash for the brain. If I could find one @ pick a part I'd be all over it tho, not having the garage door opener stuck to the visor would be a major plus!

Ya, it was Oman's write up where he drilled the holes and snaked it through the windshield frame. I thought about going that route as well and I still may do that but my plan was to upgrade to the newer style windshield trim since it cleans up the interior a bit.

I'll add a link to Omans write up for those who want to drill and run it inside the frame, thanks for reminding me! :thumbsup:

Where are the temp sensors usually hiding on the junk yard cars? Good write up BTW. Might do this soon.
The temp sensors are located behind the grill usually clipped to the core support directly below the horn. Updated write up to reflect that.

That is sooo sweet! Good job man. I appreciate the offering to help. I'm gonna have to give this a shot this weekend. I was lookin so long on this site and others for a good write up. Mad props.to you! :cheers2:
Once you get started you'll be surprised how easy it is. I am going to be doing the swap into 3 more Jeeps so let me know if you want/need more detailed pics of anything.
 
#20 ·
I have a 2004 TJ that I put a factory jeep compass/temp/auto dimming mirror in. My jeep had the wiring harness for the temp sensor and dome lights under the trim plate on the passenger side of the dash. All you need to do is pop the trim off and plug into the seven pin connector. The temp sensor harness was in the front of the radiator on the drivers side. I would assume most TJ's would have the same set up. I was able to get the harness that ran from the mirror to the connection on the top of the dash. The install took 30 minutes using all factory parts. I would check the top of my dash before you go to all the trouble of creating a new harness. You may get lucky and have the same thing I did.
 
#21 ·
Yeah, the good thing about this type of yard is they just go by what they judge something is worth or by a list of prices. How much would you pay for some "random rear view mirror" from a junk yard? They have a list and it probably says $5 or something. What does the girl working part time behind the counter know it it's a $300 from the dealer computerized rear view mirror or a $5 piece of plastic and glass from a 1976 Ford Pinto. That goes for a lot of things from u-pull-it places. You need to go there a couple of times and feel the places out. This isn't an endorsement to steal, nor is it a good example (just drunk and it's what I can think of)----most of the chicks that you pay at the place I go couldn't tell a camshaft from a crank angle sensor. A unit bearing from a u-joint. A cylinder head from a wheel cylinder. It's a junk yard and they are usually happy to get something for the stuff that they will otherwise throw away in a couple of weeks.

**And just a warning to potential pick pockets. They had a cop inspecting tool bags last time I went to the yard. Just a tip. Being vague about a part, grey area. Lying or stealing--go to jail.
 
#23 ·
Sure thing. Start by sitting in the passenger seat. Grasp the two inch trip piece that is at the base of the windshield. Start from the right side and gently pull up on the trim to remove. Once the trim is off, the plug will be laying in a cut-out area right in front of you. This connection carry the battery lead,ground, temp sensorand the LED lights. Now if you don't or can't find this cable I would highly recommend that you pirchase the harness/patch cord fro¤ a Jeed Dealer. Ones you make those two connections in the cab you are all but finished. Next go to the front of the jeep on the drivers side. ,between the grill and radiatior there is a gap or tray at the bottom of the
radiator and this is where the temp sensor has been waiting patientley. You will still need tbe sensor and mointing bracket. If you don't have a donor. The harhess sensor and sensor bracket shuld be cheap at the jeepdealer.hope that helped.
 
#24 · (Edited)
Sure thing. Start by sitting in the passenger seat. Grasp the two inch trip piece that is at the base of the windshield. Start from the right side and gently pull up on the trim to remove. Once the trim is off, the plug will be laying in a cut-out area right in front of you. This connection carry the battery lead,ground, temp sensorand the LED lights. Now if you don't or can't find this cable I would highly recommend that you pirchase the harness/patch cord fro¤ a Jeed Dealer. Ones you make those two connections in the cab you are all but finished. Next go to the front of the jeep on the drivers side. ,between the grill and radiatior there is a gap or tray at the bottom of the
radiator and this is where the temp sensor has been waiting patientley. You will still need tbe sensor and mointing bracket. If you don't have a donor. The harhess sensor and sensor bracket shuld be cheap at the jeepdealer.hope that helped.
Awesome! Thanks dude. I followed what you said. Is this the plug i'm looking for?......if this is the plug I need, is this the only connection I need inside the cab? Also, will only a Jeep mirror plug in to this connection or can I use like a chevy tahoe mirror? just in case I cant find a Jeep mirror at a junk yard...thanks again......:cheers2:



 
#25 ·
That's it! Glad yours had it too. Now, all you need is the harness that runs between the mirror and the plug you just found on the top of the dash. If it were me, I would purchase one from Jeep, for no other reason that it would be a clean, quick, plug and play install. The part number MAY be 56047087AC. I say "MAY" because the drawing I have is not real specific.

At a minimum I would purchase the pins and connector from jeep, If you have to make the harness from the mirror to the dash. This way everything will plug up nicely.

As far as a GM mirror working and plugging right up to the jeep harness I believe is a real possibility. Most OEM mirrors are made by Gentex and I would assume the connector would be the same.

Good Luck with the install.
 
#26 ·
That's it! Glad yours had it too. Now, all you need is the harness that runs between the mirror and the plug you just found on the top of the dash. If it were me, I would purchase one from Jeep, for no other reason that it would be a clean, quick, plug and play install. The part number MAY be 56047087AC. I say "MAY" because the drawing I have is not real specific.

At a minimum I would purchase the pins and connector from jeep, If you have to make the harness from the mirror to the dash. This way everything will plug up nicely.

As far as a GM mirror working and plugging right up to the jeep harness I believe is a real possibility. Most OEM mirrors are made by Gentex and I would assume the connector would be the same.

Good Luck with the install.
Sweet! I'm soo glad its there. Seems like it will be way easier. I really appreciate your help. Now all I will need is the mirror, wire harness from mirror to plug on dash, front sensor and the mounting bracket for sensor? Correct? Its happening this weekend if I can locate the parts!!
 
#29 · (Edited)
great work ! i have this mirror and the conector for about a year and never got into installing it, thanks now i have all the info! one thing I have an 03 tj when you remove the plastic windshield vent ( in front of the dashboart) there is a connector there, it appears to be prewired for this type of mirrors, does anybody know?
 
#32 ·
great work ! i have this mirror and the conector for about a year and never got into installing it, thanks now i have all the info! one thing I have an 03 tj when you remove the plastic vent windshield vent ( in front of the dashboart) there is a connector there, it appears to be prewired for this time of mirrors, does anybody know?
look up a couple posts...I posted some pics of the connect under the dash..if that is what you have then you're good...thanks to cranksterwatch!
 
#33 ·
anyone know if this will work with an onstar mirror?
my buddy has a tahoe that he is thinking of getting rid of
he said i can swap my mirror for his if it works
ill have the only onstar jeep out there :D
 
#34 ·
You may get the temp and compass to work but onstar would be another story. Onstar is a subscription service that requires a cellular based transmitter to communicate with onstar. It is basically a smart phone installed in the dash that has GPS so Onstar can locate you. Kinda like having big brother with you at all times. The compass and temp may work but Onstar woulb be a long shot.
 
#35 ·
Ok just got back from a salvage yard. Looks like I found a beaut out of a Chevy SUV. Not sure what it was cuz someone took everything off of it that had the name, It looked like a Tahoe. Anyway, can anyone tell me if that is the temp sensor? I looked all over the front of the truck and I saw this mounted below the horn in front of the radiator/AC unit. Also, I was unable to get the entire wire harness, so i took everything I could. I unplugged the 7 pin connector from the mirror and followed that all the way inside/top of the dash. A worker from the yard said it is almost impossible to get where that runs to. So, he recommended I cut the wire near the dash and take that, so I did. Now does anyone know how to connect it to that plug on top of the dash? Does Jeep or anyone sell the female connector for that plug? I figured I could solder the wires to the female connector and plug it in. Any suggestions? Here are some pics. If you need to see more of the harness I took, I can take more. Thanks!



 
#36 ·
Looks like you found everything you needed. That is a temp. Sensor you may want to check and see if it will mate up with your factory harness. As far as the connector to complete your install, I would try your local jeep dealer and see if he can get the pins and connector for you. Also, if you go to the dealer I would see if they can get the temp sensor bracket too. If you can't get the bracket you can make an "L" bracket and use a self tapping 10mm screw to bolt the bracket to the factory hole. Good Luck and have fun!
 
#37 ·
i was only kidding about the onstar
i was really wondering if an onstar mirror would work or the lack of the cell transmitter would cause problems
 
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