Coulee Region Fieros
Serving Fiero lovers in the La Crosse and Eau Claire areas.
Auto Dimming Mirrors
Just a little article about installing an auto dimming mirror
Introduction:
As I am sure that you know any trucks or vans that pull up behind you, blind you. I am lazy and I don’t like flipping the little switch to dim your mirror. Plus, I also knock my mirror off when I do it. I figured that this would be pretty easy, and it was with the exception that I broke my windshield… The mirror works well now that it is in. Also, with the way that the Fiero overhead council is, it is easy to wire.
General Notes about Auto Dimming Mirrors
This is where your public library will came in handy. Once you find a mirror go down to the library and look up the wiring diagrams for your specific mirrors. These directions are going to be specific to a 1994 Road Master mirror. However, most of the mirrors are very similar. There will probably be five wires. Two of the wires are grounds, one hot lead that needs to be on full time (this is for the lights,) one hot lead that is powered up with the ignition (this is to power up the mirror dimming function,) one hot lead that comes on with the curtsy lights (I skipped this one because Fieros have enough lights come on when you open the doors.) Next, make sure that you test the mirror before you pay for it. The mirror that I got was free so I didn’t test it. When I got the mirror, it was in a few pieces and the junkyard assumed that it wouldn’t work. It might be hard to test the mirror out in the car if the wiring has been picked apart. If the wiring is intact hook the battery up or as in my case I have a jumpstart pack that I use. You need a flash light for this part to make it easier. Look on the back of the mirror and find the ambient light port. All it is is a hole in the back of the mirror that takes a reading of the ambient light and compares it with a light meter that is on the mirror glass. Now, you can also bench test the mirror, hook the black wires up to ground and all the other leads (every color but black) up to a hot source. Now to test. Whether it is in the car or bench testing, all you have to do is cover the light meter in the back and shine the flash light on the mirror glass. If the mirror dims, then it is looking good. Now, turn off the flashlight and uncover the hole in the back, if the mirror un-dims you are in business. It does not un-dim as fast as it dims. If it is not working make sure that the mirror is powered up. There is some sort of on/off switch on all of them but they vary from mirror to mirror. An auto dimming mirror works as follows. A processor in the mirror takes readings from the ambient light sensor (the hole in the back of the mirror) and the sensor in the mirror glass. A comparison is made between the sensors when the light intensity in greater in the mirror glass sensor, the mirror dims. The mirror is a piece of glass with a reflective layer on the back. Then on top of that layer is a layer of plastic that dims when an electric charge is run through it. Then on top is another layer of glass. I don’t really understand the photoelectric layer (the plastic that darkens when an electric charge is applied to it) so I am not going to get into it. There are also mirrors that have a motor in them that "flip" the mirror. I have never seen one.
Instillation of Auto Dimming Mirror
With my auto dimming mirror, the metal tab that holds the mirror to the windshield is a different size than the standard Fiero tab. I figured that I could just grab the metal tab on the windshield and give it a pull and it would just pop off. I was very wrong, I gave it a pull and the windshield broke. I don’t know how to get the tab off without breaking the windshield, you are on your own here, please be careful. I’m going to focus on the wiring. The overhead council has a connector in it so that is can be separated; I wanted to keep it that way. I used a computer power connector for this purpose. I found a 3-way plug. I cut it up; I then wired one plug to the mirror and tapped the power lines with the other plug. Then if I need to disconnect the overhead council it is very easy. Now to start on the wiring. In the overhead council there is a common ground for the switches, I tapped the ground wire for the ground for the mirror, both of the ground wires. The ignition hot wire was the hardest to run. I ran a single strand wire under the head liner, to the driver’s side A-pillar to the fuse panel, I then crimped a spade on the end of the wire and put it in an open slot. Currently, I do not have an inline fuse but will be putting one in as soon as I can. Remember the wire running through the A-pillar will be right against a metal ground. If it shorts you will be in trouble. Next is the all time hot. I just tapped the orange wire under the over head council. I put it all together and it works well. This is great for interstate driving and in town driving at stoplights and what not.
By: Rob
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