Many moons ago, I replaced the stock seats in the Land Cruiser with some Corbeau Sport seats. They are . . fine. Some things about them I like, some I don't. But they are good for longer trips, so I've kept them. I also have leather cover replacements for the stock seats squirreled away, for when I feel in the mood for that.
Anyway, when I ordered the Corbeau seats, I opted for the heated option. I verified that the truck came wired for heated seats, so I bought factory switches and popped them in.
With the help of a friend, I got the right connectors and terminals to hook up to the factory harness. Not rocket science, but I put it off for a long time.
Recently I decided it was time to hook it all up, so I dug into the wiring info my friend sent me.
So . . when the seat is on LO, 4 is hot and 3 is GND. When the seat is on HI, 5 is hot and both 3 and 4 are GND. A bit odd, but ok.
The Corbeau system is totally different and comes with its own switch. I did some thinking and ended up concluding I needed a relay system to give the Corbeau seat what it wanted, stole the power feed from the Power Seat circuit, and everything should have worked.
The Corbeau system has a power feed, a GND, and then a rocker switch with yellow, green, and blue wires. These all connect to a little electronics box that actually does the seat heat circuit control (including monitoring a thermistor inside the seat, which is cool). My relay system takes the power feed for the seat heat and turns it into the yellow wire either connecting to the blue wire or to the green wire - which is the same thing the Corbeau switch does.
I built relay harnesses with the Corbeau connector and the factory connector.
With everything done, I plugged it all in and confirmed that the seats do, in fact, heat up when turned on!
However, they do not turn off. Both sides do the same thing. I stripped down the setup completely, until I was only connecting power and GND to the seat. And after a few seconds of being plugged in, it would start pulling a few Amps of current. VERY strange. I called Corbeau and they picked up immediately - no phone tree or anything - and the first person I talked to was able to help me. They said they never recommend using other switches, of course. But they did send me new control boxes. I'll try those next, just haven't had time to dig back into it.
Weird, eh?