How To: Install a Compass / Temperature Rear View Mirror

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Derek Wheeler

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Great write up. I have a dual display in my 02, and autodim without displays in the 88 and 99 (OH consoles have the compass/temp in them instead).

Two things to point out.

1. You don't have to wire anything to the backup light signal, I haven't in all the mirrors I've installed and they will still work normally.
2. You can disable the autodim by holding the "Temp" button until the green indicator light turns off.

Here is the plug and wiring diagram. if you connect the green backup wire to 12V it will NOT dim.

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I just got a mirror and harness off a 99 denali. The harness also has a 2 pin connection with orange and yellow w/black strip that also plugs into the mirror. Whats that pin for?
 

88GMCtruck

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I just got a mirror and harness off a 99 denali. The harness also has a 2 pin connection with orange and yellow w/black strip that also plugs into the mirror. Whats that pin for?
The GMT400 Escalade/Denali has some additional functions for the truck's automatic lighting that ran through the mirror.
 

Luis Jimenez

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Hi today I got a compass mirror from a 99 escalade I also got the temperature sensor from the same truck, I used a 12v source to test the mirror but the only thing displaying on the mirror is a letter C which I assume it means it is on calibrate mode then when I push the temp button nothing is showing on the display, I connect the green/black and the brown wire to the temperature sensor, any ideas why isn't working? Thanks.


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89RCLB

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If you have a digital multimeter set it for 20K ohms and test the probe, my probe measured 18.37 ohms. Rather odd that you didn't get an OC (open circuit) or an SC (short circuit), usually it'll display something...
 

Luis Jimenez

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If you have a digital multimeter set it for 20K ohms and test the probe, my probe measured 18.37 ohms. Rather odd that you didn't get an OC (open circuit) or an SC (short circuit), usually it'll display something...

It doesn't display anything just the letter C and when I press the comp button the display is completely black, also sometimes de little green light comes on all the time, and nothing happen when I press the temp button, also I test the green and brown wires and seem that both has ground but one is brighter than the other when I test them.

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DirtBag

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This pic was extremely helpful when I did mine!! It is a perfect spot to tap into the reverse light circuit. The rest of the wiring is really straight forward. I'm loving my mirror!



I realize this is an old thread but it was recently helpful to me. The only thing I'd like to add is the image below. It shows the location of the Lt Green Reverse wire, backup lights wire, Back-up Lamp Feed, reverse light hot wire, etc. Whatever you want to call it. :biggrin:

There is a two wire harness, with a four wire connector, that goes to the back of truck. You can easily locate it by laying under the driver's side of the truck just behind the front wheel. It's on the inside of the frame. Follow that harness up to the engine bay. See below.

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lxe4

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can the overhead DIC and the mirror share a temp sensor or do i need 2?
 

swsmith1971

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From my understanding of the wiring pinout that I got from stroker52 pin 4&5 are used to tell the outside mirrors to dim when the inside mirror dims. I'm not actually aware of any external mirrors for the GMT-400 that have the ability to dim.

I'm new to this forum, and I haven't read on much further than this, but I purchased a set of Auto Dimming, Heated Power Mirrors (outside L & R) that came off a 99' Escalade and they mounted just fine to my 1992 GMC Sierra. However, I'm still working on how to power everything and wire to the compass/temp mirror. From the schematics that I have, the rearview mirror and the outside mirrors all connect through that same harness, and the temp sensor along with the auto dimming features.
 
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