I have a 2003 Vert. The auto dimming feature just stoped working --- when I push the button on the mirror at night with the headlights on, the green light does NOT come on and the auto dimming feature does not work. All the lights on the mirror are working so I assume the fuse is not the issue and I haven't checked it. Any ideas here? the car just has 9,000 miles on her and I don't think I've hit this button more than 30 times as long as I've owned the car so I can't believe it has failed already. Any ideas here or do I have to order a whole new mirror .

Thanks for any help on this issue

 

Actually there is another circuit for the auto dimming feature. Check fuse #2 in the IP fuse block. I had the same problem and it turned out the auto dimming feature and the vanity mirror lamp lights on the visors are on that fuse and the wires to them were melted together at one of the mirrors and was shorted out, causing that fuse to blow. I think the fuse for the other lamps is #21. Good Luck.

 

Vanity mirror light work fine --- so i guess it must be the on/off swithch that failed and I'll have to pull & replace the mirror assembly. This is a crazy set-up anyway; if you have to reach up and fiddle with the mirror at night to turn the system on, then it might as well be an all manual system to begin with. Either that, or it needs to be replaced with a totally automatic dimmer system that you get on just about every other car.
Just another example of stupid engineering ---- ugh!

 

I have a mirror out of a 21k mile C5 if you want to keep everything original.

 

Might check Fuse #21 in the IP Fuse Block! It feeds 12V to point "A"
----------------------------------------------------

 

Since all the lights on the mirror work and all the lights on the vanity mirrors work, I doubt it can be any fuse --- but i will pull the #2 and #21 fuse and take a look.

I've studied this schematic and for the life of me I can't figure out how to read it ---- is there any website that will explain how to read this thing?

Thanks

 

This might help a LITTLE!
-------------------------------------------------
Automatic Day-Night Mirror Description and Operation
Inside Rearview Mirror with the Automatic Day-Night Feature System Components
The inside rearview mirror with the automatic day-night feature system consist of the following components:

Inside rearview mirror
Driver outside mirror with the automatic day-night feature
Power and Ground of the Inside Rearview Mirror
With the ignition ON, ignition voltage is supplied to the mirror from the BTSI BU fuse in the I/P fuse block.
Ground for the mirror is provided by SP202.
Inside Rearview Mirror with the Automatic Day-Night Feature System Operation
The inside rearview mirror uses 2 photocell sensors. One sensor is the headlight sensor, located on the rear side of the mirror. The headlight sensor is used to determine light conditions present at the mirror face. The other sensor is the ambient light sensor, located on the front of the mirror or windshield side. The ambient light sensor is used to determine light conditions present at the mirror. With automatic day-night feature enabled, the mirror uses ambient light sensor to determine the exterior light condition. With a low light condition detected, and a high light condition from behind at the headlight sensor, the inside rearview mirror will automatically darken the face of the mirror.

In the daytime, the mirror is in a normal state because of the high light condition that is indicated by the ambient light sensor. With the gear selector lever in the REVERSE position, backup lamp supply voltage is supplied as an input to the inside rearview mirror. In night time conditions only, the mirror monitors this input to disable the automatic day-night feature which allows the face to gradually change to a normal state. This allows the driver to see objects in the mirror clearly when backing up.

Driver Outside Rearview Mirror with the Automatic Day-Night Feature Operation
The inside rearview mirror will also darken the driver outside rearview mirror. The inside rearview mirror supplies a low reference circuit and a signal circuit to the driver outside rearview mirror. Refer to Outside Mirror Description and Operation in Doors for further description and operation of the driver outside rearview mirror.

Switches of the Inside Rearview Mirror with the Automatic Day-Night Feature
The inside rearview mirror has three switches that perform the following functions:

The switch at the center of the mirror is used to enable or disable the automatic day-night feature. With the ignition in the ON position, depress the switch to enable the automatic day-night feature of the mirror. A green indicator will illuminate on the mirror when the automatic day-night feature is enabled. To disable the automatic day-night feature of the mirror, depress the switch again.
The other two switches are for turning the map lights on the mirror ON and OFF.

 

I was sure it was not any blown fuse because all rear view mirror lights were working and all vanity lights were working and because I've been having trouble with my back, i didn't want to crawl under the passergers side dash to get at the interior fuse box. WELL, it turned out to be the #21 fuse --- and even when I pulled the #21 fuse, the maps lights which were on because the door was opened, still remained on with that #21 fuse out ---- GO FIGURE! I almost put that fuse back in without looking at it since the map lights were still on. Anyway the problem is solved CHEAPLY and thanks to all those who chimed in with suggestions. I've learned over the years to check and eliminate ALL of the easy/simple stuff first before you start ordering parts assuming the worst.

Thanks again to all

 

Good deal, Glad to hear is was just a fuse

 

The fuse blew again --- I need to check if it blows when I turn the headlights on --- I think the mirror dimming circuit is somehow tied into the headlights. I need to do more testing so I kknow exactly when the fuse blows. Electrical problems --- the worst!

 

This may be helpful, but what is a BTSI BU and what fuse is that and what is the SP202?

 

With my dark tinted glass,my auto mirror never worked anyway!

 

Hmmm..I wonder if the fuse blows when you put the transmission in reverse?

 

Unplug your miror and try it,at least that will let you know if it is an internal problem.

 

 

BTSI
Brake Transmission Shift Interlock

 

You're Right ---- When I put a new fuse in ---- the mirror works fine, but when I put the car in reverse, the fuse blows. All this stuff is on the same circuit so the real problem/short is with the back-up lights.

Now I need help with diagnosing a short with the back-up lights so i think I will start an new thread --- back-up lights short.

Thanks

 

Man...I'm two for two today.......I'm gonna go get me an ice cream.

 

 

The reverse light switch in my M12 failed, in turn causing that 21 fuse to blow. Replacing the switch and then the fuse fixed my problem. Easy way to tell it's #21, the little amber led in my mirror was out.