I wouldn't be surprised if the sensor was tied into the rear view mirror. My '08 XLT does it. Didn't realize it was even on there until about 4 or 5 months after I got the truck and it did it. I find it annoying at times because it does it randomly...or so it seems. No complaints about it though.

 

I have them on my 2007 lariat

 

I got it on my 07 but my buddies 07 does not have it.

*edit*
Looking over the window sticker (I bought the truck used) under optional equipment

Deluxe mirror package $245.00
*Power signal heated mirrors
*Elec rear view mirror

Having this option is absolutly awsome.

 

have it, like it

 

my fx2 has it too. i've also got a set of power folding mirrors w/ puddle lamps but no dimming feature. i want to install them cause it sucks to fold the mirrors in manually everything i put the truck in the garage. hmmm, what should i do?

 

can you maybe swap the glass out? i have wanted to upgrade to the tt mirrors but didnt want to loose the dim function. also i think it is tied into the sensor for the rear view mirror cause all the time i have my 4wheeler in the back no light from cars behind ever reach the sensor on the rear view mirror and neither side or rear dim.

 

Check here for '07 FX4 Lux. Pckg.

I just wish the passenger side had it, too.

 

It came with the Deluxe Mirror Package option on mid '07+ trucks.

I love it. I wanted to swap out to the tow mirrors but I will not as they do not have this feature and I like it so much.

 

Actually mine is an early 07 and I have it. Build date 12-06-06

 

I've got them on my 07 Lariat. They are power folding, heated, auto dimming on driver side, with turn signals and puddle lights. Don't know part number or where sensor is.

 

Sorry to drag up a thread from the ice age, but I recently bought a set of mirrors off a fellow on this website and put them on my 04 lariat. After installing them and looking at them, I noticed a line around my drivers side mirror and thought "what the devil is that?" Dawned on me it had something to do with an auto dimming mirror. Either way, Im writing to see if anyone knows if the wires are already pre-installed in an 04 for auto dimming. It doesnt get dark her for another two hours and I really cant wait that long for an answer haha