How to: Add a Temp / Compass rear view mirror

silverunicorn

Original poster
Member
Dec 4, 2011
327
There have been so many questions on this and so many threads in another forum, maybe this will help someone.

DISCLAIMER - I ACCEPT NO RESPONSIBILITY TO ANY DMAGE DONE TO YOUR VEHICLE BY PERFORMING ANYTHING IN THIS HOW-TO

This How-To is designed to help you install a rear view mirror that has the temperature and compass in it if you do not have those features already. This was written based off my install on a 2006 Trailblazer LS with manual HVAC controls, as well as information from other forum members.

Here we go :smile:

1) You need to make sure you can even do this mod :yes:. Look at the back of your rear view mirror. Does it have a 16 pin plug on the back?

plug.jpg


If no, STOP HERE

If yes, then keep reading.

2) Obtain new rear view mirror with compass and temperature display. I found mine on E-Bay. Keep in mind that GM used the same mirrors on MANY models, so it does not necessarily need to be from a Trailblazer. Mine was from a Silverado :yes:

The important thing is to get a mirror that matched the FEATURES your vehicle has (Onstar, Passenger side air bag indicator, integrated phone, etc.)
If you don't have Onstar or air bag indicator, you can get a mirror with those, just those features will not be operational.

3) Get other required parts.

You will need:
1 SENSOR - GM Part # 15047946
1 CONNECTOR - GMPart # 12101856
2 Female terminals -Delphi Part # 12191818
2 Cable seals - Delphi Part # 15366021 (these are available but honestly, I did not use them and have not had an issue)

In addition, you will need wire, butt end connectors or soldering iron / solder, wire loom (if desired) and basic electrical knowledge.

4) Once you have all the parts, you can begin!

Step 1: Unplug the 16 pin connector from the back of your existing mirror.

Remove mirror. There is a set screw at the base of the mirror. This is a TORX screw.

setscrew.jpg


Once screw is removed, the mirror assembly should slide up and off the mount on the windshield.

Step 2: Install new mirror. Slide new mirror onto the base on the windshield and insert set screw. DO NOT OVERTIGHTEN THE SET SCREW!!!!. Connect the 16 pin connector.

At this point, if you turn the truck on the compass should work, but the temp area will read OC. OC stands for OPEN CIRCUIT and this lets you know there is an issue with the sensor or wiring to the temp sensor.


Step 3: Open Hood (duh).

Step 4. Locate the hole in the top of the radiator shroud where the sensor should go. It will be at the front of the vehicle, just about in the middle.

051103TS09-155.gif


The sensor you buy will have a mount attached to it. It will look something like this:

sensor1.jpg


The bottom part is the mount and it is NOT used in our application. You can easily remove the sensor from the mount.

Also locate the plug just behind the battery on the drivers side firewall of the truck:

firewall.jpg


Now the fun begins :smile:

Connect your temp sensor to the sensor wiring harness. The wires on the harness are only about 12 inches long. You will need to use wire and butt end connectors to extend these wires to get to the connector in the firewall. If you don't like solderless connectors, then do what you need to do.

Once that is done, you can pop the sensor to the hole in the radiator shroud. It should pop in there easily.

Once in, it should look like this:

Trailblazer -
Sensor.jpg


Envoy:
envoysensor.jpg


Locations should be the same, pictures are for reference. Nothing needed to be removed to get to those locations.


Now that the sensor is installed, you need to connect the 2 wires you extended to the plug on the firewall. The 2 female connectors listed in the parts needed above come in here. Connect those to the ends of the wires you extended.

Then feed them up to the purple connector in the firewall.

The connector has a purple colored plastic wire seperator on the outside. If you are standing beside the driver's fender looking at the fusebox, the connector is directly in front of you, closer than the fusebox, mounted on the inner fender. Now looking at the right side of the connector (the side facing the cab), you will notice the green/black stripe and brown wire at the top of the connector. Also notice, that on the left side of the connector, you will have 2 blank places. These two blanks are where your temperature sensor wires go. Pull the two rubber plugs out and you can temporarily test your sensor here until you get your wire routed.

firewall.jpg

wiring.jpg


Once those wires are connected, the temp sensor should be operational! Those are the 2 spots needed, but in my personal experience the wire position in those 2 spots are irrelevant.

working.jpg




Clean up your wiring with wire loom for that factory-ish look :yes:

516413045_828957a4d3_o.jpg

516388072_9f9a15b103_o.jpg


Chris

Thank you to MTT, APPSTATEGIRL, ROADIE, SONICAIDE and any other member whose picture or information I used. Most pictures were mine, but some were taken from the multiple threads on this subject, as well as the internet. If I used a picture of yours that you would like removed, please PM or e-mail me and I will remove it. This is a resource only and is not to be used for any capital gain.
 
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HARDTRAILZ

Moderator
Nov 18, 2011
49,665
This is simpler than I thought. I would not mind having the extra info. Now I need to check my mirror.

Thanks and nice writeup.
 

coolasice

Member
Oct 27, 2013
1,019
Northern Maine
I tried to install one of these in my trailblazer but the compass display would not light up.... Can someone who added this check if they have a 12v or 5v at the connector pin 12? I don't have any wire there and might need to add one....
 

coolasice

Member
Oct 27, 2013
1,019
Northern Maine
coolasice said:
I tried to install one of these in my trailblazer but the compass display would not light up.... Can someone who added this check if they have a 12v or 5v at the connector pin 12? I don't have any wire there and might need to add one....
Nevermind... The mirror is the culprit... finally figured it out... my wiring was not the same as in the service manual as my connector near the battery is a 8pin while the manual says it is a 10pin....
 
Mar 30, 2016
1,465
KSA
Hi everyone just got back from the junkyard with the mirror and sensor. Sadly in my hastiness I forgot to get the connector to the sensor. I went to our dealership and damn that thing is pricey. But my question is if I were to pull the connector with the harness from a junked truck, would I still need to extend the wire or what would the procedure be otherwise. Thanks to all for the input
 

Blckshdw

Moderator
Nov 20, 2011
10,697
Tampa Bay Area, FL
if I were to pull the connector with the harness from a junked truck, would I still need to extend the wire

That depends entirely on how much wiring you can remove from the donor truck. If you get enough that can reach, great. If not, or parts of the wiresame are damaged, then you'll have to splice in good wire, or extend it.
 
Mar 30, 2016
1,465
KSA
That depends entirely on how much wiring you can remove from the donor truck. If you get enough that can reach, great. If not, or parts of the wiresame are damaged, then you'll have to splice in good wire, or extend it.

How much would I need to pull to avoid having to splice or dice. Just not wanting atm. Cause i don't really get the procedure and i don't want to have a dead truck
 

Blckshdw

Moderator
Nov 20, 2011
10,697
Tampa Bay Area, FL
The connector on the inside of the fender is in the same place in all our trucks.

This mod has nothing to do with drivability, so you can't disable the vehicle trying this.

If you don't understand the procedure, pull up this thread on your phone if you can, pop your hood, stand next to the battery and re-read it while looking in your engine bay. That will help.
 
Mar 30, 2016
1,465
KSA
Just cut the two wires at the plug next to the fusebox and pull them back to the sensor.

Ok I got it now. Cause when i went to see the wiring it was all nicely wrapped up etc. So I'm thinking of taking the connector by the fusebox all the way till the sensor.

Thanks for the input
 

Blckshdw

Moderator
Nov 20, 2011
10,697
Tampa Bay Area, FL
:confused: Are you asking how to solder wires together? Cuz that's what it sounded like...

As for how much you have to extend it, the only person who can answer that is you. You have to put the harness in your truck and look at it. That will show you what you need to do next. :yes:
 
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Mar 30, 2016
1,465
KSA
:confused: Are you asking how to solder wires together? Cuz that's what it sounded like...

No no. I am not one for soldering connections :biggrin:

Sensor 1.jpg

This is how much I have got of the sensor and wiring harness. My question would be what would be the way to extend this? Add wires all the way to the purple connector by the fusebox? And I tried to just plug in the Brown and Green wires as stated in the purple connector to test it out. There seems to be a stick like thing in there and hence no connection is made. Any ideas ?? :confused:

Thanks everybody for tolerating my tiny brain :bonk:
 

jsheahawk

Member
Jan 16, 2013
533
Kansas City
Yep. Solder (or whatever means you feel comfortable with) those wires to longer wires, and connect those longer wires (by your preferred, non-car-fire-causing means) to the purple connector.
 
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Blckshdw

Moderator
Nov 20, 2011
10,697
Tampa Bay Area, FL
Those are plugs to keep out dirt/moisture. You have to pull them out first, then stick the wires in.
 
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Mar 30, 2016
1,465
KSA
Then you would be reading the temperature of a hot engine bay, not the ambient air temperature outside of the engine bay, as it's designed. :no:

Yeah seemed to be a a tad above the right temp. So I found some wire and was thinking about extending it. But the wire is quite thin. Should that be a problem ?
Wire 2.jpg Wire 3.jpg Wiring 1.jpg
 

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