I am going to share my procedure to upgrade my 2014 Silverado Crew LT from DL8 to DL3 mirrors. I am doing this to show my end results that I was able to achieve with the help of others and their write-ups.
My 14 Crew had power adjustable heated mirrors and I did NOT have auto dimming or park assist. The last two items I did not research so if you need info on them it won’t be in this write up. I added power fold turn signal mirrors with puddle lights to my Crew, and this is how I accomplished it.
There are UTube videos on how to remove your door panels so I won’t waste time on that procedure. Removing the rubber trim from around the top of the window is made easier with the window in the down position which allowed access the mirror bolts so I won’t discuss that either. Once your door panels, inner cab kick panels and mirrors are removed you will most likely have only 7 pins in the harness on the door that plugs into the mirror harness. If that is the case you will need to wire directly a power wire for the turn, power wire for the puddle light and add a ground for the turn signal light as it has its own ground, but I will show another option later on that point. I ran just the two needed power wires from the BMC area to my mirrors.
First off I used door switch Part number #23154702 for the power fold mirror switch. There are discussions on another part #, and from what I read this is the one for the Trucks. I chose to add in to the mirrors a connection to unplug the mirrors later in case the mirror ever had to be replaced. The 2 new power wires that I had to run are needed for turn and puddle lights, and is located in pin 1 and 13 of the harness from the mirror. My wire colors were (pin #1) Orange/black for the puddle light and (pin #13) Blue/red for the turn signal. This is the same on both side mirrors left and right. I chose a point to cut the wires and solder in some connectors, using a female end for the puddle light and a male end for the turn. That way I did not confuse the wires when making the connection. I also staggered the connection to avoid a bulging area in the wiring. I used some shrink tube on the cut ends not used to prevent any issues with un-shielded wires.
Here is a pic of my mirrors mounted at this point.
Now the process is to run the wire from the cab to the connectors I put in place through the rubber housing where the other wires are located. I used a piece of a coat hanger after pulling the rubber boots loose and my wires came through on top of the connector on the body side of the truck, just fish it through with a coat hanger. This process is time consuming so take your time so not to damage any wires in the harness.
I also had to provide a ground for the turn lights, this was stated in the write up that I followed by schlegle1. I did my ground like he did, combining the ground wire needed to the one ground already completed in the original mirror harness. On my mirrors, I have 1 black/white wire and 2 black wires. They all seem to be the same size wire, but the 2 wires that you want to join to add a ground for the turn signals are the black/white wire in pin # 5 and the black wire in pin # 11. The black wire in pin # 8 is the mirror Heating Element Supply Voltage. DO NOT USE PIN #8.
I have installed my mirrors and confirmed that power adjustment, power fold, turn and puddle lights along with heat functions all work using this procedure. I am moving forward with identifying wires at the BMC and completing this mod today.
This information has been acquired with the help from ngiovas, schlegle1 and special thanks to BeauTie for the link to the up fitters manual. That will help me confirm wire connections at the BMC.