How To: Retrofit an autodimming rear view mirror with compass and temperature readout

[Nas Escobar]

Hmmm.... Do you have the original pigtail for your Gentex mirror? I would assume the connections are the same with the wire nearest to the center is 12+, the one next to it on the left is neg and the 3rd one would be the equivalent to the ground for the reverse.

Unless the car's wiring hooks up to the last three near the driver's side which in turn only powers the lights, meaning that you're also not powering the auto dim feature since the compass doesn't light up. Because you don't have the temperature, your lights may be wired up in where the temp would be and I feel perhaps the Donnelly wiring is different from the Gentex, being mirrored instead of pnp. It might be something to look at. Bench test that Gentex with just the last 3. If the lights work but the compass does not, there's your problem.

[wws944]

I powered up the Intrigue GNTX-221 mirror on my bench, and it turns out that pin 7 also needs +12v for the compass to work.

[Nas Escobar]

So, to confirm, the wires from the lighted mirror do not plug and play?

[wws944]

Originally Posted by Nas Escobar

So, to confirm, the wires from the lighted mirror do not plug and play?

Almost. The Alero mirror connector has wires on pins 1, 2, and 6. These are for +12v (when the car is either in ON or the computer says to keep it energised for a few minutes for Retained Accessory Power mode), ground, and switched ground (door is open) respectively.

For the Intrigue mirror, pin 7 also needs +12v - but when the ignition is on. In theory one could jump it across to pin 1. But then the RAP would keep it on even when the car is turned off - for a few minutes anyway. Which would be annoying.

[Nas Escobar]

Oh I see. I figured that would have been the case when I wrote it. I was going to suggest cutting off the stock Donnelly connector and cutting/splicing the wires to match the Gentex one.

[wws944]

I really don't like cutting up factory wiring. So if/when I install the GNTX-221, I will reuse the original 7-pin connector. I will simply remove the female pin 7 and its orange wire from the Intrigue connector shell, then insert it into the Alero connector shell. Then splice in a wire to run down the A pillar as you describe above. Same with pin 3 and its green wire - which is the reverse light trigger.

BTW, I would imagine both the compass and autodim depend on pin 7. Have not confirmed the autodim part yet.

[Nas Escobar]

It does. The compass and autodim run off the same powered source.

[wws944]

Additional note: I was at a local Pick-N-Pull yesterday and noticed that some Aleros came with a map light mirror even without a sunroof. The one in particular I was looking at was a '99. It used a square 2x2 pin connector that is the same, or similar, to others that GM used in the 1990s.

If someone with an Alero already has one of these mirrors and wants to upgrade it, the existing wiring can be reused. But again, the mirror would still need a 'hot when ON' wire. Also one would need to check whether the 'switched ground' connection might be a 'switched hot' instead. I have seen these '90s mirrors both ways...

[Netuddki]

I know, it's an old topic, but I thought it needs an update.

Before you make the hassle with reinventing the wheel, look at Aliexpress (I am not affiliated in any way).

There you can get auto dimming mirrors with Android and GPS, touchscreen and bluetooth and WiFi and whatnot for $120.

http://www.aliexpress.com/item/Andro...996846514.html

I have a DVR mirror in my car (hardwired with mini USB to the interior light under the roof cover) which works very good, but now I want to upgrade to an auto dimming mirror DVR.

A simple one you can already buy for $60.

There are even mirrors with compass and temperature (without DVR) just like those Gentex mirrors for $70.

So my advice is to look around before you make your life harder.

[Nas Escobar]

Not an old topic, just a how to.

I've seen these rear view mirrors before, but that just be a bit too much for some people. Plus, rear view mirrors at the junkyard usually sell for $10 and then all you have to do is buy wiring. The point of this mod was really a cheap way to have temperature, compass and no night headlight glare in a car that never came with the rear view mirror option. Most of these just had map lights.

[lildrummer420]

Anybody having trouble after installing the temperature sensor? Mine is saying it is 110 degrees outside when it is only around 70.

[Nas Escobar]

Originally Posted by lildrummer420

Anybody having trouble after installing the temperature sensor? Mine is saying it is 110 degrees outside when it is only around 70.

That may have something to do with where you placed the sensor. If you put it near the engine, it's going to read the ambient temperature in the general area of the engine bay.

Where exactly did you place your sensor?

[lildrummer420]

Originally Posted by Nas Escobar

That may have something to do with where you placed the sensor. If you put it near the engine, it's going to read the ambient temperature in the general area of the engine bay.

Where exactly did you place your sensor?

I placed it opposite of the tailpipe behind the rear bumper.

[Nas Escobar]

The temp sensor is supposed to be at the front of the car, in front of the radiator. That's the way they come stock in most cars. It's probably reading off because of the area heat. Remember that heat can spread out beyond its source and heat can maintain in well insulated areas (like the rear bumper).

Random question, but why did you choose to put it in the back of the car?

[lildrummer420]

Originally Posted by Nas Escobar

The temp sensor is supposed to be at the front of the car, in front of the radiator. That's the way they come stock in most cars. It's probably reading off because of the area heat. Remember that heat can spread out beyond its source and heat can maintain in well insulated areas (like the rear bumper).

Random question, but why did you choose to put it in the back of the car?

OK thanks I will try moving it. It was easier to run under the door sills along the tail light wiring harness.

[Papa Rad17]

I could see a lot of heat getting trapped back there from the muffler. Maybe some reflection off the pavement as well?...

[Nas Escobar]

Originally Posted by lildrummer420

OK thanks I will try moving it. It was easier to run under the door sills along the tail light wiring harness.

You can always run out to the front by following the harness to the firewall and poking a small hole to run the wires through. That's how I ran sub wires on both my old Grand Am and my Camaro.