The auto dimming feature on my rear view mirror has never worked. I’m finally at a place with this truck that I can knock out some “luxury” to-do’s and have checked all the interior fuses. Outside of that, I don’t know where to begin. I really appreciate any insight!

It’s a 98 Ram 1500 w/ the 5.9L Magnum

 

Is it plugged in to the harness?

 

It is!

 

I believe there is a switch on the bottom of the mirror for that as well....... If it's on, has power, but doesn't work, replace it.

 

correct, its s push button from the bottom I believe, and a green light.

Ill check my fuse layout and my service manual, i would guess it shares a service fuse with the overhead display and/or vanity mirrors.

Edit: It shares fuse 11 with overhead console, ground appears to go through the backup lamp circuit? I'm not sure if this is a shared ground or if this was a feature so the auto dim disabled in reverse, something I never paid attention to in the past.

 

Do you have window tints? I do and and a lot of the time not enough light hit's the sensor to activate it. At dusk you can test it by shining a flashlight into the sensor then you will see a difference in the mirror.

 

Do you mean replace the switch or whole assembly? And thanks for replying!

 

No window tints- it’s clear as a fishbowl in there

 

Whole thing. I doubt individual parts are even available. Of course, the mirror itself likely isn't either..... Junkyard, or ebay may be the only source.