So the vehicle I am working with is a 1993 toyota 4runner, base model (DLX?), factory simple. The seats have been on their last legs, so I've been searching for replacements for a number of months. I really wanted Toyota seats, but couldn't find anything that was either affordable or in better condition than mine. After looking into other make/model sources, I happened upon a near-new set of front seats from a 2003 Subaru Outback. My route of installation ended up being cutting the bracket legs off of the donor/donee seats, and welding the Toy brackets legs onto the Subie sliders. Worked great for the passenger seat, and the method will work fine with the driver seats also, however I've run into a rod block: the subaru driver seat is power... only.

The recline and lumber is manual, but the fore/aft tilt and the vertical positioning are done via motors. My problems is not with the mounting, but rather the integrating of the electrical components into my current 4runner harness. So far, here is what I understand...

- The Subaru seats originally drew power from a 30A slow-blow-fuse located in the engine bay. Seems like a lot for a couple small motors, but this circuit also handled the power windows and the door lock timer.
- The Subaru also ran power through a circuit breaker. No details can be found about this breaker. I am still scouring the subie forums.
- I am confused about switched vs. accessory power. Switched is with a key in the ignition, and accessory is without? I don't see the need for the seat to be adjusted unless someone is in the seat, but my girl is almost a foot shorter than me, so perhaps pre-seated adjustments could be knee and back saving...
- The Subaru manuals I have been able to look at don't point to a relay for the power seat mechanism (not to be confused with the seat heater, which I do have, but am not hooking up right now. Seat heat HAS relay, power seat adjust does NOT.) A relay, if I am understanding correctly, is designed for controlling high current draws through circuit not necessarily designed for it? Is that right? It's like an intentional parasite, drawing from Circuit A to power Circuit B without overloading Circuit A. I've looked at a few illustrated diagrams of relay circuits and I've STILL not sure I'm reading that right. Long story short, I'm not sure if I need to wire up a relay for this single seat, or if a 30A fuse would do the trick...

BTW, the very posts on YT I did find about adding power seats are about 3rd gens, where wiring was already there from the factory and it was more of a matter of modifying existing harnesses. I will be continuing to look for more answers.

-Chris

 

Hi Chris,
First important thing is to remember that the stock harness of the truck may not be designed to handle the power for the Subaru seats.

To be safe, do NOT integrate the seat system power circuit into the existing harness. Power it directly from the battery through a 30-amp fuse dedicated for powering only the seat motors, heater if any, etc. Copy the power supply circuit that Subaru has, including circuit breaker it it has it, but tap that directly from the battery as above ^^.

This way, power needed by seats will not have to pass the main fusible link. IF anything goes wrong with the seat system, it would not blow your main FL- critical to the vehicle running. Instead it will only blow the fuse dedicated to the seat system.

A Relay uses a switch designed for low current to energize its coil. The coil in turn closes the contacts. The contacts will carry high current needed to run a seat motor or heating element. It's like Master-Blaster in Mad Max. Master says one thing, Blaster does it. Explanation of how relay works, and actual video of starter relay actuating are included on this post.

IF I were to do this, I would take power for the switches (remember this is low power) from "Accessory" circuit. That's the part of circuit that stereo is connected to. This way, you would need a key in order to activate any of the seat circuit, but not need to put it in IGN position. Why subject the ECU to power when I only want to adjust seats?