My Gmt900 Dl3 Mirror Upgrade Story

OhOneW6 · December 14, 2008

I have a 2007 2LT Avalanche. I wanted the DL3 folding mirrors. This is what I went through to get them.

First I bought a set of mirrors from someone who upgraded his DL3 mirrors to the trailer mirrors. Fortunately he had the same wood grain trim as my truck so I was able to get the drivers door switch and trim panel from him as well. We plugged the drivers mirror and switch in before we parted and it worked. I thought that was all I needed to test.

I rushed home and installed the mirrors and much to my surprise the passenger mirror would not fold. The only added feature on the passenger side that worked was the turn signal. I called my dealer and asked if they could fix this by flashing the BCM. They told me there was no way it could be done. They have tried it and it was impossible. All the programing is based on the VIN and my VIN does not have that option.

I then called my salesman and convinced him to let me swap the passenger switch with a DL3 optioned truck for testing. We pulled the switch from a truck on the lot and put it in my truck. The passenger mirror functioned correctly with this switch. Even though the part was identical right down to the part number my switch would not operate the mirrors and the borrowed switch would. I further tested this by putting my switch in the DL3 optioned truck and the passenger mirror did not fold.

After talking to the parts dept we figured out the memory module was in the switch and it would have to be programed for the DL3 option. I called service back and asked them to put my switch in a DL3 optioned truck, flash it and give it back to me. They agreed to do this for me on the phone but when I showed up to get it done, they refused to do it. That was and will be my last trip to that dealership for anything.

I then called the preferred dealer of the person I bought my DL3 mirrors from uses. They were extremely accommodating even though it was a Pontiac/GMC dealer and my truck is a Chevrolet. He said it was no problem to fix this. He also stated they did not need to put my switch in a DL3 optioned truck. They could fix this with a Tech II.

Before they flashed it, I noticed that by installing the switch form the DL3 optioned truck it added the park tilt feature in the DIC. I don't use it but i thought it was cool that I had it now when I didn't before. After they flashed it this feature was gone. After talking to the tech he said the park tilt was only available with the seat upgrade. He then flashed the truck again changing the seat option and the park tilt feature returned.

Three suggestions for those with dealers who say it can't be done:

1) See if they will put your switches in one of their DL3 trucks to program them

2) Swap switches with a friends truck with the DL3 option and have the dealer flash that truck.

3) Go somewhere else

Part numbers I used:

The drivers side switch - 15906881

The wood grain bezel - 15920638

This may or may not work for your truck. Not all 900 platform trucks are wired for this option. From what I can tell if you switch looks like the picture 1 you can do the upgrade and have fully functioning folding mirrors. If you switch looks like picture 2 then you do not have the switch with the memory module and you truck will not be wired for the folding option. There is more info in this thread.

Picture 1

Picture 2

(MichAngler, hope you don't mind but I stole a copy of your pic.)

Long story short, Some (but not all) can and the DL3 mirrors to a GMT900 truck and have all the features work.

Zembonez · December 14, 2008

Long story short, you can and the DL3 mirrors to a GMT900 truck and have all the features work.

That's pretty cool.

Thanks for going to the trouble to post your results. We all SHOULD do that. Usually, once something is working, you never hear from people about it again.

MS3DALE · December 14, 2008

Cool,Thats nice to know.

BuckFeverZ · December 14, 2008

Good mod!

I wouldn't care if I didn't have the power fold option I just want the turn signals

slomo007 · December 14, 2008

I'm secretly hoping to have two things (and only two things) happen to my truck while parked somewhere: stolen wheels and stolen mirrors, so that I can file that insurance claim and get the power fold feature in the mirrors and also top it off with some nice aftermarket rims.

Well, I guess if they want to take the lint trap seats that would be fine too.

MS3DALE · December 14, 2008

Good mod!

I wouldn't care if I didn't have the power fold option I just want the turn signals

Well then,Go here....MUTH MIRROR

BTW....I like your wheels! What kind are they?

MS3DALE · December 14, 2008

Well, I guess if they want to take the lint trap seats that would be fine too.

BuckFeverZ · December 14, 2008

Good mod!

I wouldn't care if I didn't have the power fold option I just want the turn signals

Well then,Go here....MUTH MIRROR

BTW....I like your wheels! What kind are they?

I've looked into those Muth kits a few times but just can't justify spending the coin on those.

My wheels are 17x9 Helo Maxx 6's.

jbannick18 · December 15, 2008

How much do those mirrors cost from the dealership? Anybody know. BTW nice mod!

asilverblazer · December 15, 2008

Just to prevent somebody from doing this mod and wasting money...

It worked on this truck because it had the correct style of switches to begin with. If not, it would not have been a simple reprogram.

OhOneW6 · December 15, 2008

Just to prevent somebody from doing this mod and wasting money...

It worked on this truck because it had the correct style of switches to begin with. If not, it would not have been a simple reprogram.

Exactly. I edited my original post to try and make this more clear.

stevewallace · December 16, 2008

Can someone point me to more info on the Park Tilt function? I searched for it and only found two threads (including this one). I have a Silverado LT2 with the power fold mirrors and I'm always tilting them in order to park the truck. Did you find that it could be enabled later just by flashing the ecm?

OhOneW6 · December 16, 2008

Can someone point me to more info on the Park Tilt function? I searched for it and only found two threads (including this one). I have a Silverado LT2 with the power fold mirrors and I'm always tilting them in order to park the truck. Did you find that it could be enabled later just by flashing the ecm?

The option to turn the park tilt feature on or off is in the DIC. I thought the power folding mirrors were only available on the 3LT and LTZ. If you read my first post you can see what I had to do to get the park tilt option after I did the DL3 mirror upgrade.

stevewallace · December 17, 2008

Thanks, I'll look again. BTW the Silverado only went to LT2 before LTZ. The 09's though I don't think have an LT2 option.

Can someone point me to more info on the Park Tilt function? I searched for it and only found two threads (including this one). I have a Silverado LT2 with the power fold mirrors and I'm always tilting them in order to park the truck. Did you find that it could be enabled later just by flashing the ecm?

The option to turn the park tilt feature on or off is in the DIC. I thought the power folding mirrors were only available on the 3LT and LTZ. If you read my first post you can see what I had to do to get the park tilt option after I did the DL3 mirror upgrade.

stevewallace · December 17, 2008

Thanks, I'll look again. BTW the Silverado only went to LT2 before LTZ. The 09's though I don't think have an LT2 option.

Can someone point me to more info on the Park Tilt function? I searched for it and only found two threads (including this one). I have a Silverado LT2 with the power fold mirrors and I'm always tilting them in order to park the truck. Did you find that it could be enabled later just by flashing the ecm?

The option to turn the park tilt feature on or off is in the DIC. I thought the power folding mirrors were only available on the 3LT and LTZ. If you read my first post you can see what I had to do to get the park tilt option after I did the DL3 mirror upgrade.