2004 Impala Rearview Mirror Wiring Identification
 

Here's the situation. I'm back into the Impala world again (used to own 2-1965s and 2-1967s). I recently bought a 2004 Impala for my daughter who is out of state for school. I'm doing some minor mods for her and 1 of the things I'm doing is changing out the rearview mirror. Currently it has a regular rearview mirror with map lights. I bought an auto-dimming mirror with map lights and a compass (GNTX-221 - some reports mention that this also has a temp readout but there is some debate on it. Not a big deal to me either way.).
<O:p></O:p>
I've installed a similar mirror on a different model car so I am aware of the work that needs to be done. I've done a lot of research on the web regarding the GNTX-221 and its wiring harness (believe me, the web is great for this stuff).<O:p></O:p>
<O:p></O:p>
Anyway, what I would like to know is the existing wiring for the 2004 Impala rearview mirror with map lights only. It has a 7-pin plug that I was hoping would fit into the GNTX-221. When I asked my daughter what went into her mirror, she told me it was a 7-pin harness. She also said it had 4 wires going into the harness. Starting from the driver's side, she said pin-1 is Black, pin-2 is open, pin-3 is Green, pin-4 and pin-5 are open, pin-6 is Gray and pin-7 is Blue.<O:p></O:p>
<O:p></O:p>
Can anyone help me to identify what each of these wires is? From what I can tell, this won't fit "pin to pin" to the GNTX-221 because I believe pin-2 on the GNTX-221 harness is a Ground. I appreciate any help you can provide!<O:p></O:p>

The schematic I looked up only shows three wires. But I am willing to bet your four wires are as follows: black - Ground, Green - Reverse, Gray - B+, Blue - IGN
I could be wrong so don't take it as corect please. Get your trusty multimeter out(or buy a cheapy) and test all the wires. You may have to de-pin the wires and insert them into the new connector, or just move them around to line up with what the instruction say.

Thanks for the reply. I'll check out the wires with a multimeter for sure. Just curious, what 3 wires were listed in the schematic?

Not sure it matters, but the existing mirror is not autodimming, but just has the map lights. I would have thought that they would only have needed to run a Ground and B+ to the harness to make the map lights work since that would be the only thing drawing power.

However, perhaps they wired all of the harnesses that way for efficiency reasons. Regardless, thanks again for your help! (Problem is, I won't be going to see her for a month so I won't be able to install it until then!)

The schematic I was looking at must have been for a different option....here is what you should have....


Inside Rearview Mirror (w/o UE1)

<table border="1" width="95%"><tbody><tr> <th rowspan="1" colspan="4" align="center" valign="middle">
http://gsi.xw.gm.com/image_en_us/gif...153/153632.gif

</th></tr> <tr> <th rowspan="1" colspan="2" align="center" valign="middle">Connector Part Information
</th><th rowspan="1" colspan="2" align="left" valign="middle"> </th></tr> <tr> <th rowspan="1" align="center" valign="bottom">Pin
</th><th rowspan="1" align="center" valign="bottom">Wire Color
</th><th rowspan="1" align="center" valign="bottom">Circuit No.
</th><th rowspan="1" align="center" valign="bottom">Function
</th></tr> <tr> <td rowspan="1" align="center" valign="middle">1
</td><td rowspan="1" align="center" valign="middle">BRN
</td><td rowspan="1" align="center" valign="middle">141
</td><td rowspan="1" align="left" valign="middle">Ignition 3 Voltage
</td></tr> <tr> <td rowspan="1" align="center" valign="middle">2
</td><td rowspan="1" align="center" valign="middle">BLK
</td><td rowspan="1" align="center" valign="middle">1750
</td><td rowspan="1" align="left" valign="middle">Ground
</td></tr> <tr> <td rowspan="1" align="center" valign="middle">3
</td><td rowspan="1" align="center" valign="middle">LT GRN
</td><td rowspan="1" align="center" valign="middle">24
</td><td rowspan="1" align="left" valign="middle">Backup Lamp Supply Voltage
</td></tr> <tr> <td rowspan="1" align="center" valign="middle">4-5
</td><td rowspan="1" align="center" valign="middle">--
</td><td rowspan="1" align="center" valign="middle">--
</td><td rowspan="1" align="left" valign="middle">Not Used
</td></tr> <tr> <td rowspan="1" align="center" valign="middle">6
</td><td rowspan="1" align="center" valign="middle">GRY
</td><td rowspan="1" align="center" valign="middle">157
</td><td rowspan="1" align="left" valign="middle">Interior Lamp Control
</td></tr> <tr> <td rowspan="1" align="center" valign="middle">7
</td><td rowspan="1" align="center" valign="middle">DK BLU/WHT
</td><td rowspan="1" align="center" valign="middle">149
</td><td rowspan="1" align="left" valign="middle">Courtesy Lamp Supply Voltage
</td></tr></tbody></table>

Again, thanks for the information. That does seem to match more what my daughter said she saw. With that in mind, I am going to have to tap into an "ignition source" for Pin-1.

From my research so far, it appears as if the recommendation is to tap into the pink wire on the ignition harness. I assume this harness is behind the dashboard ignition (duh!). Is it easily reachable without having to do much dash removal? I'm not too crazy about having to go from the mirror over to the pillar and then down to the dash and then back over to the ignition. Seems like a long ways to go. (So much for the saying "the shortest distance between 2 points is a straight line"!!!!) If there is a better source at the fuse box or ????, I'd be interested in trying.

I really do appreciate the help!

The brown wire should be the ignition source, an should work fine for your application.
If memory serves me right, I think the connector should just plug right in. Just double check the pin location, move them around if you have to, and just plug it in

You are correct! Initially she told me that there were only 4 wires. Once I pushed her to double-check today, she relented that she did miss a wire at Pin-1 in her initial check and the more she looked at it, it was BROWN.

So, the pins match up exactly to your schematic and also to the Gentex 221. It will certainly make my job simple. The harness should plug right in. My only issue is to make sure the old mirror comes off the windshield smoothly and the new one goes on smoothly.

I really appreciate all of the information - it has made my job a lot easier! Thanks again....

Follow Up
 

Just a quick follow up. Finally got to my daughter's car and installed the Gentex 221. Took a total of 5 mins. Plug and play with no wire issues. Worked like a charm! Thanks for all of your help...

awsome...good to hear and thanks for the follow-up

hi -
I happen to stumble across this thread, as we have an ongoing problem with son's 2004 Impala LS and the auto-dimming mirror.

It appears there is a loose connection or broken wire such that the green led (auto dim) and the 2 map lights don't always work unless you very carefully jiggle or move the wiring going into the mirror. Haven't looked, but it is a pain - not sure if a connector problem, wiring into the connector, or the socket on the mirror, or even the circuit board inside the mirror.

Any thoughts on where the problem might be - from any experience :)