I know someone has already replied regarding this, but I wanted to also weigh in and offer my two cents.
All credit for disassembly of the seat comes from
this post. I followed it to a T and had no issues with disassembly or re-assembly.
As the other poster noted, took about an hour to two hours to take the seat apart. Wasn't difficult at all, just tedious work. I actually used zip ties instead of hog rings, as it helps to prevent short circuiting of the heating pads. I read about it a loooong time ago on this board and shelved it until I was ready to do the mod. Also, using zip ties was considerably faster, as I have read.
I used
these heated seats. I wanted so badly the OEM ones (or at least the backlit ones that fill the blanks), but everything I read on this forum, as well as some FJ cruiser ones, noted how difficult the wiring was in regards to voltage and using a heated seat with a hi-off-low switch vs a dial switch like the OEM one. In the end, though, I really wanted a high quality unit and went with the Dorman one. I bought two kits, but in the end only installed them on the driver's seat. My wife has heated seats in her Infiniti and never uses, so I knew she wouldn't care for them in my car. In the picture, the switch on the left is for my lower back and butt, and the one on the right is for my upper back and thighs. I am a tall guy so there are times when I only want the upper back on for dry heat for a kinked back or sore muscles from work.
Wiring took me considerably longer since I wanted the switches in the OEM location and wanted to keep the wiring and relays in the seat cushion and not underneath it. I tapped into two unused locations in the cabin fuse panel which were hot on ignition only. I used 15A fuses in the Add-A-Fuse, and there is a 10A in-line fuse in the actual heated seat wiring.
Though I was working on other things in the car when I installed these, it took me probably 6 hours. However, I went really slow as I have never taken upholstery apart in any vehicle before, and as the other poster pointed out, I could do this much quicker now that I have already done it once.
Hope this helps. I can answer any additional questions people have.