I bought a set of the 2006 towing mirrors for my 2004.5 LLY CC GMC Sierra LT to replace the regular power mirrors with turn signals. They bolted right on, plugged in and everything worked. When I started driving it I noticed that sometimes when the engine is turned off and/or started that the mirrors would go out and up and leave me looking off into space. I set the "driver 1" setting on the armrest/door but it keeps happening. If I press "driver 1" it doesn't go to the preset position. I got my manual out and studied it, thinking that maybe I missed something about how to set it but I didn't see anything new. I have not been able to detect a pattern or particular event that makes it happen, seems like a random thing when turning off and/or starting the engine.
Anybody else seen or experienced this? Is there a flash update I need to get for the different mirrors?

Maybe those mirrors "know" more about you than you realize. ;) j/k

I'm wondering if the programming for them might be different. Either that or "something" is reprogramming them for alien abduction lookout mode.

The only thing I can think of is it's the reverse assist option that may be going screwy on you. With your original mirrors, they tilted down when you put the truck in reverse, correct? If so, the truck still thinks you have those mirrors but if the wiring is a little different.. maybe it's screwing with your mirrors. I would think a reflash to the "basic" mirrors (no turn signal) would fix it. Just my $0.02

I think the BCM needs to be reflashed for the mirrors.

Jim

One of the first things I thought of was the reverse assist option which I never liked and always kept off. I checked and it is disabled so that's not it. I guess I'll check with the dealer and see if I can find somebody that even knows what I'm talking about.