I have looked for a long time to found out how to install r171 seats in my r170. I know the manual seats are straight forward swap but the R171 power seat use a control module to move the seat. I tried to power the control unit up by supplying it power and ground but that didn't work. The control module requires an interior CAN network signal which the r170 doesn't have. So what is the solution? Well it turns out the non seat memory seat switch on w164 as the same mounting points on the seat switch. So seat switch will mount to the r171 seat. The w164 seat switch has one extra connector that supply the switch with power and ground. The other connector will need to be rewired so that the correct wires go to the correct seat motors. The seat switches I ordered already had the pig tails to that made it easier to do the rewire. The only other issue doing this is it leaves an ugly hole in the seat trim where the seat memory buttons where mounted. So what I did to unscrew the seat switch and swapped the front parts that has the seat memory buttons made on to it. I would rather have buttons that don't do anything than have a hole in the seat trim.
I can list how I rewired the seat but I would encourage you to look at the wire diagram to make sure you. Also I would bench test the seat before solder and make sure you wired it correctly. The wires switch polarity so if you wire it wrong it will move the incorrect way. The R171 Passenger seat also has the WSS system. I removed everything except the part coming out of the seat cushion. The R170 car needs to have a passenger seat cushion sensor installed or the srs light will be on. You can order a seat cushion sensor bypass on eBay. Passenger seat wiring: connector 1 pins 1 and 3 use the power wire coming out of the vehicle that is a fuses and relay control power so it will be safe to wire to the seat switch. Pins 2 and 4 are ground. Driver seat is the same way. See picture for what wire goes to what. I also made a YouTube video that may help once it uploads I will add a link. PS I'm dyslexic so take it easy on my spelling and grammar lol.