Added Rearview Mirror with Compass and Temp

[mrphoenix80]

So I really missed the temp display in my Jimmy,and wanted one in the Envoy.
So I got a factory mirror from a 04 Tahoe with all the options I wanted and none that I didn't (Onstar).I installed the mirror and found the autodim and compass work great as well as the airbag indicator, but the temp reads "OC". So I got all charged up to run the wires from the mirror to the grille and install the sensor. However when I went to add the wires I found that they are already there! OK so how far do they go? I found out they end in the 10 pin connector on the fender next to the underhood fuse box. Sweet! So all I had to do is go from the underhood connector to the grille and install the sensor.
So now for the next step I got the sensor and found some terminals that fit it. Now because I don't have a connector and I am to impatient to wait for one to come in. It is "arts and crafts time" I used hot glue to secure my wires in the sensor. Then I added them to the connector by the underhood fuse block. Now I have my "factory compass/temp/autodim" mirror install and functional.

Sorry for the pic it did not transfer over well but I think you will get the idea.

 

[brandongill8]

Do all models have the wiring to do this? I bought a mirror with Temp and compass in it and mine now has nothing, so there are no wires going down to the mirror. Are the wires just up in the headliner and I just need to get them down, plug it in and put a temp sensor under the hood?

 

[mrphoenix80]

I don't know about the mirrors with no wires to them. All the ones I looked at had a mirror with some kind of plug. And all of those had the wiring under the hood. The underhood wires are easy to spot. To see if the wires are under the hood look at the connector on the left fender above the fusebox. Where the red and black wires are in the pic above will be empty cavities, but on the other side of the plug is brown and green wires that come from the mirror.

If you have no wires to the mirror. You will have to look in the headliner to see if the wires are there. If not, you have a lot to wire, maybe too much. You need an Ignition 1 feed and a ground also the 2 wires out to the sensor. The compass sensor is mounted to the mirror so the power and the ground will make it work. The rest of the pins are for the onstar buttons, air bag indicator, and a B/U lamp signal(that I don't know why it's there).

 

[brandongill8]

I have the wires under the hood. So I guess I will just have to remove the overhead consol and see if its up there.

Thanks!

 

[Mark20]

Most of the time the wiring harness supports all possible options so manufacturing doesn't have to match up the right harness with the right vehicle on the line. Messing that up would be a real problem especially if panels are added before options are actually installed (and finding the needed plug is not there). Having to tear apart a vehicle to replace a harness isn't a cost effective thing to do in any book.

 

[rjpoog1989]

I don't know about the mirrors with no wires to them. All the ones I looked at had a mirror with some kind of plug. And all of those had the wiring under the hood. The underhood wires are easy to spot. To see if the wires are under the hood look at the connector on the left fender above the fusebox. Where the red and black wires are in the pic above will be empty cavities, but on the other side of the plug is brown and green wires that come from the mirror.

If you have no wires to the mirror. You will have to look in the headliner to see if the wires are there. If not, you have a lot to wire, maybe too much. You need an Ignition 1 feed and a ground also the 2 wires out to the sensor. The compass sensor is mounted to the mirror so the power and the ground will make it work. The rest of the pins are for the onstar buttons, air bag indicator, and a B/U lamp signal(that I don't know why it's there).

The back up light signal wire I so that auto-dim mirrors do not dim when the vehicle is in reverse. This wire must be connected or the auto-dim will not work correctly. Also, if you don't have a mirror with wiring already you should have the wires tucked up in the headliner.

 

[mrphoenix80]

The back up light signal wire I so that auto-dim mirrors do not dim when the vehicle is in reverse. This wire must be connected or the auto-dim will not work correctly.

I suspected it had something to do with that, but was not sure.
I was just happy I did not have to string the wires very far for the temp sensor.

 

[slamfire]

The rear view mirror on my 04 trailblazer (with compass, temp.) is floppy. It seems that these little tabs that a ring fit over to provide tension for holding the mirror in adjustment became brittle and broke. Do I need to replace the whole mirror or is there another way to fix this? Thanks.

 

[HiOSilver]

I've got exactly the same problem. I've ordered a replacement mirror from EBay, and I'll see if the ring of plastic fingers is replaceable. I'd like to keep my original mirror since I've got my radar detector wired into it, so I'll swap them if I can.