Thank you to @Seanhump
. My power seat retrofit worked out beautifully! Extracted the power seat harness from one purchased on eBay, a tedious process since I preserved the rest of the harness by carefully unwrapping and re-wrapping the affected sections.
The donor car was a beauty with lumbar air bladder and air lines etc. which my seats didn't have. Planning to re-sell the intact full-car harness on eBay for someone adding Airscarf, heated seats, lumbar, or apparently about every other option to their R171.
Loving the power seats. Feels a bit higher and provides a steeper angle sloping back/down in the base. More luxurious than the manual version.
Harness came with fuse box, all fuse holders and fuses. After a meticulous process to extract the required cables from the full harness it was just as tedious to get it into the car. Use disposable gloves to keep the gummy black cable wrap adhesive off skin and everywhere else.
The difficult part of the retrofit was routing the wire under the back of the center console. I could not for the life of me get the rear console section to budge after unfastening everything I could find and pulling a lot harder than I should have - luckily nothing damaged. Somehow - with much perseverance, some blood, and choice words heard more often in rap songs and cable tv shows - managed to route the end of the cable under the console in-place and carefully pull it though.
Second worst part was figuring out how to pop open the $#@&*!% CAN voltage distribution connector. Second only to the passenger footwell power socket connector, this black-on-black, tight fitting, "is that a seam, or not a seam?" plastic housing is actually an ancient puzzle out of a Dr. Who episode or Indiana Jones movie. I should have
installed the SmartTop that's been in my cabinet for years but by then was too tired, sweaty, slightly bloody, running out of new swear words, and - most of all - loosing light. Yes there are pictures about this in other posts but I needed a video. Going to post one before long when I finally install the SmartTop soon.
In my car the power seat functions w/o the key inserted (the way I want it), and the memory function works w/o any programming. No easy entry function, need to read up on that but don't really care.
Make sure the heaters work in the new bases!!
I must have damaged the driver side heater in the base since it's no longer heating, but the passenger side heats up in base and back. However, to me this is actually an improvement not a bug. The driver base used to get too hot for my taste and made my thighs feel like it was going to burn them. Now with only the back heater I can actually enjoy heated seats for the first time. Passengers side is toasty in base and back. I will probably double check the connector and continuity just for closure when adding the SmartTop. Had i know before what i know now, I'd probably have disconnected the power connection for the driver side base years ago.
This is a great and relatively straightforward upgrade. Great feature in terms of look, comfort and functionality.