Power seat conversion

What you've already found in the wiring diagram shows you that the downstream of that 30 A fuse comes out of the instrument panel junction block at connector 2D pin 13. A green wire runs from there to connector LR2 pin 1, then to connector RX1 pin 1 at the seat (where the wire turns white and goes to the lumbar switch).

This post and this one will show you more about finding your way around the wiring diagram for the additional information you're looking for; this one will give you some more information about the instrument panel junction block.

 

I added power seats from a Lexus Ct 200h. I got the ignition on signal from the cigarette lighter in the dash and ran that back under the front carpet to the seat. Then I ran a 12 volt power wire wire forward under the carpet fused right at battery, Very very carefully snaked the wire to around the hybrid battery and fan. AVOID THE HYBRID BATTERY or you or the car could be killed. I covered ends of wire with lots of electrical tape to get it around all the electronics and be as non conductive as possible. Don't poke around with a bare metal wire or a metal snake -please be safe.
Then I used power wire from the cig lighter to turn on a relay to direct power from the 12 volt battery to the seats I did not want seats to be powered all the time.
I did not want to mess with any wires under the dash or fuseblock because I had moved seats in my old Gen 2 and got some trouble codes so this time stayed away from the OEM wires, console or fuseblock. If I did it again I would run two wires from dash (driver and passenger) from cig lighter (with fuses) and two wires from the battery in rear of car with two fuses (driver and passenger) and then put a relay under each seat (driver and passenger). Be aware seats from CT 200h are too low for the Prius and need some fabrication.

 

I looked my installation and to make it even easier I recommend using a orange 16 foot 120volt household extension and start the installation from the 12 volt battery in back of car. Most extension cords have green, white and black wires. Use one wire for the ground and one wire for ignition signal and one white for power. I used green to ground to body near battery. The 15amp fuse should be on power wire right at the connection to the battery and then add a 30amp automotive relay. You are sending the ignition signal backwards to the relay and the ground and the power forward to the seat. To safer you could run that orange cord in trunk away from the hybrid battery to drivers side corner of the trunk. Remove the side panel from the trunk and avoid the battery altogether or find another route. Run the orange cord under the sill plate or under the carpet. The ignition power can run under the carpet. Your ignition power can be from dash cigarette lighter or from the console That is for one seat the driver side. I am obviously not a electrician but this worked for me.

OEM Prius power seat should fit and not be too low like a CT200h, but I will try to post photos the bracket I had to cut up and bend the legs to lower the computer under the drivers seat.

 

You are welcome, also if you find a six pin connector on a passenger power seat going to the seats 4 pressure sensors and you car has old 4 pin connector for the 4 pressure sensors just take out that 6 pin harness from power seat and use the 4 pin harness from your old non power seat. And you may have to swap the seat beat buckle on new seat.
Avoid connections to the car, just use 12v battery and do not take car apart you have no ECU or code issues.

 

this gets more complicated when you want features like heated seats and cooled seats which usually have 3 power settings each. Sigh. Anyone know of how to make a aftermarket head unit work with more modern power seats? I want that massage feature on long cross country trips for the back

 

Hey Chapman, thank you so much for the great information!

do you think it would be alright to run bot FL and FR seat power wires to Connector 2D pin 13 (for FL) ? I was thinking run two separate wires to the junction box, combine, add connector and push into connector 2D pin 13

I assume the RH seat power pin is on one of the connectors on the firewall side of the junction box which has been very difficult for me to get to.
Just not sure if that is going to be too much runnning two seat motors off a single 30amp fuse?

thanks in advance!

 

The explanation is simpler than that: there is no RH seat power pin, and no PWR SEAT FR fuse. Only the FL seat was ever powered, and the only part powered (in my 2010 anyway) was the lumbar support.

So you are into custom territory if you are adding two powered seats, and especially if those are powered in more ways than just the lumbar pump. You may want to test them on the bench and see what kind of current they draw.

If there's any problem, you might be able to solve it socially (agree with your passenger that you won't adjust your seats at the same time) or technologically. A techno-fix could be a left-right selector switch you could take turns with (kind of like the mirror motor controls), or a more clever circuit that would use a higher-impedance detector to see when the left or right seat controls are being used, and supply power to one or the other, first come first served.

 

this is very good information thank you!

odd thing is that I have existing fuses in the following locations circled in green for FR power and FR heat power

also, in this Toyota heated seat instructions it shows to remove and insert a pin for RF seat heat power on connector 2A pin 21? photo attached

if I am understanding you correctly, I could theoretically connect both power wires to the single power seat pin but just not use them both simultaneously ? Would it work better or even possible to pin the RH side to one of the open fuse slots and then add a fuse?