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Thanks for the info. Do you have any photos of when you looked behind the headliner ? Also please keep me posted if you are able to explore that Y connector. Hopefully it’s left there for XL models to add plug and play dimming mirror.
So I finally got around to exploring my headliner. The harness Y was nothing more than a loop doubling back ending at the mic. 🙁. But you can’t let small things get you down. What I have found is most of the main wiring harnesses have all the wires, it’s the secondary ones that are vehicle specific. If you pull off the trim on the right c pillar, there is a connector up high which has all the wires necessary for auto dimming mirrors and other functions. So I plan to run wires, inserted into the secondary harness connector (with the proper pins), through the headliner to a new mirror. From there down the A pillar, under the dash and through the door wiring harness (using proper pins) to my mirror. Some wiring diagrams show my door harness wired for a self dimming left mirror; I need to test it to see exactly where I terminate it. I’ll keep you informed
So I finally got around to exploring my headliner. The harness Y was nothing more than a loop doubling back ending at the mic. 🙁. But you can’t let small things get you down. What I have found is most of the main wiring harnesses have all the wires, it’s the secondary ones that are vehicle specific. If you pull off the trim on the right c pillar, there is a connector up high which has all the wires necessary for auto dimming mirrors and other functions. So I plan to run wires, inserted into the secondary harness connector (with the proper pins), through the headliner to a new mirror. From there down the A pillar, under the dash and through the door wiring harness (using proper pins) to my mirror. Some wiring diagrams show my door harness wired for a self dimming left mirror; I need to test it to see exactly where I terminate it. I’ll keep you informed
Loop
C pillar connector (from bottom)
Thats excellent. If you get it working please update this post I would really like to have this functionality with my truck.
I’ve read other posts since where xlt owners have replaced the headliner wiring harness with a lariat one to hook up the auto dimming mirror. So I did more investigating via wiring diagrams and saw that making your own harness that plugs into the mirror and using pins in the oem connector on the other end would be fairly easy. All wires are there in my xl wiring harness in the C pillar so no running of wires down the A pillar. This would be much cheaper and easier, no full removal of the headliner or harnesses switching. 👍
The BCM controls the mirror and I can’t find a line in the speadsheet to flash it with Forscan. So if someone out there knows that piece of the puzzle don’t hesitate to inform!
You are on the right path. If I had to make a educated guess there is probably no activation required in the BCM. I swapped mirrors from the base to the heated / turn signal and all function is there without enabling anything in Forscan. So it maybe the case of just buying a EC mirror,making your own wire harness and finding the correct molex plug that will fit in the c pillar harness. Should just be plug and play.
Hope so, I checked all the wiring to the driver side mirror, it’s all there so I’m good to go. All I need are the pins that I ordered, attach them to my wires
and plug them into the correct spots in the terminal...they come Monday!
My notes, not clean but has all the info for my truck 2018 XL. The wiring diagrams are for a 2017 since they haven’t released to new drawings yet. I have found most everything is the same except a few things. One was the plug on the c pillar, which I had to just trace the wires to make sure I used the right ones, but the colors didn’t not change, thank you ford!
Ground
Harness
Wires inserted into existing plug
Front view
Female pins for C pillar
Originally Posted by 20Truck
Where did you get that harness from ? And do you have the part number for the inside mirror ?
The harness I made from simple automotive wire, oem plug WPT1294, female pins to plug directly into the headliner harness (in previous photos). The mirror itself is BU5A-17E678-LA which I purchased on eBay for $50. I hooked it up today and it all worked.
The fact is is it took a lot of research of wiring diagrams etc, and I was carful making the harness. You only need five wires if you plan to dim your outside mirror too, three otherwise. So the wpt1294 has 16 wires, I used a jewelers screwdriver to remove the unused pins so it would be neat. I also kept the pigtails flat to the point at which the ar soldered to the longer wires. The makes it fit nicely under the headliner.
Last edited by Tbsheets; 07-17-2018 at 10:21 PM.
Reason: Adding drawings
You are on the right path. If I had to make a educated guess there is probably no activation required in the BCM. I swapped mirrors from the base to the heated / turn signal and all function is there without enabling anything in Forscan. So it maybe the case of just buying a EC mirror,making your own wire harness and finding the correct molex plug that will fit in the c pillar harness. Should just be plug and play.
Cannot thank you enough for this write up. It is excellent and has all the info needed to do this conversion. Did you have to remove the headliner or do you think it would be possible to fish the wiring harness while it is in place ?
07-10-2018, 10:19 PM
Long week
