Auto dimming gremlin

[boydnate]

New to forum and chasing a gremlin.
2008 Suburban with auto dimming rear view mirror that I understand controls the auto dimming feature in the drivers side mirror. Both mirrors are dimmed and will not un-dim. Visible harness wiring is undamaged and sensors are clean and when tested by shining light or covering them have no affect. My question is, is there a fuse that controls just this feature? I have pulled and checked all the I/P fuses and all are good. If no specific fuse to check, does someone have a wiring diagram for the harness or be willing to post which wires/pins to check for making sure it’s a mirror vs wiring problem. Thanks in advance for your help

 

[Just Fishing]

press and hold the power button on the mirror for like 10sec to turn it off?
Any difference?


I had issues with the side auto dimming mirrors in my 03 s10.
after a few years of sitting in direct sunlight in the morning, they finally went all weird on me.
Like double vision/blurry, but never the rear view mirror.

 

[Just Fishing]

I have to wonder now if the tech2 can see/interact with the auto dimming mirror....


If it can, there should be some codes.
I assume it would be the body module...

 

[Doubeleive]

if they are still like the gmt800's there is a sensor in both the side view and rear view mirrors, either one could probably cause the problem.
I would think if the associated fuse was burnt they would just not work and would default to off
so one of them may be faulty, the only way I can think of to test it if there is no option with a tech 2 is to ohm test both sensors
a simple test would be to unplug the rear view mirror and see if that changes anything, if not then it could be the side view mirror.
in either case if you unplug the rear view it should undim because the dimming fluid takes a small electrical charge to work

 

[boydnate]

press and hold the power button on the mirror for like 10sec to turn it off?
Any difference?


I had issues with the side auto dimming mirrors in my 03 s10.
after a few years of sitting in direct sunlight in the morning, they finally went all weird on me.
Like double vision/blurry, but never the rear view mirror.

Thanks for the reply but yeh unfortunately I’ve tried everything. It’s down to finding a fuse or chasing the wiring

 

[Just Fishing]

Thanks for the reply but yeh unfortunately I’ve tried everything. It’s down to finding a fuse or chasing the wiring

I'm more curious if the light on the mirror turned off and if the mirror went back to normal?

 

[boydnate]

if they are still like the gmt800's there is a sensor in both the side view and rear view mirrors, either one could probably cause the problem.
I would think if the associated fuse was burnt they would just not work and would default to off
so one of them may be faulty, the only way I can think of to test it if there is no option with a tech 2 is to ohm test both sensors
a simple test would be to unplug the rear view mirror and see if that changes anything, if not then it could be the side view mirror.
in either case if you unplug the rear view it should undim because the dimming fluid takes a small electrical charge to work

Unplugging doesn’t change anything. From the reading of done the electrical charge is just required to change the gel inside from dim to undim and back again but not to keep it dimmed. When you say “tech2” is that a specific piece of testing equipment?

 

[Doubeleive]

Unplugging doesn’t change anything. From the reading of done the electrical charge is just required to change the gel inside from dim to undim and back again but not to keep it dimmed. When you say “tech2” is that a specific piece of testing equipment?

it should only dim when voltage is applied as far as I know and have experienced. might try getting a used one and try it, very easy to swap out.
otherwise yes a tech2 is what the dealer uses to test various systems on the vehicle, currently a clone tech2 runs around $350-400

 

[BG1988]

Unplugging doesn’t change anything. From the reading of done the electrical charge is just required to change the gel inside from dim to undim and back again but not to keep it dimmed. When you say “tech2” is that a specific piece of testing equipment?

power needs to stay applied for it to work..so a faulty sensor might be why

 

[intheburbs]

Disconnect the battery for 10 minutes. See if that "reboots" the mirrors.