Step one, Take apart the back of the center console
I used the cigarette lighter / light for constant power and for my switched light switches
Run the wires through the center and down on both side through the center of the floor where your original cables are.
I took my ground right off of the original harness (closer)
You will also need a switched wire with the ignition. I took my switched power source from under the dash. In my case, I just spliced into one of my guages.
In all you will need 4 wires (ground,hot,light switched, and ACC (ignition) switched. I used, brown,red,blue,& white
Wiring section: Wiring E32 seats into an E23
Gray with Black stripe: Switch this wire with the lights
Red with Yellow stripe: Constant power (12v)
Large Brown: Ground
Smaller Brown with Tan (light brown) stripe: Ground
Purple with White stripe & Green with Black stripe must be spliced together and be switched with the ignition (ACC)
Red with Black stripe: 12v Hot (constant)
Gray with Black Stripe: Switched with lights
Green with Black stripe/ Yellow dots: switched with ignition (ACC)
Seats should have power and the heated seats should work.
*My passenger side heated seat did not work, I think there was a broken wire in the harness. I fed the switch with a feed and all was well. Brown w/ blue stripe under the heated seat switch had no power, ran a power source and all is well.