I recently installed OEM heated seats into my 1999 Subaru Forester. Before I began, I headed to the boards and FSM references to understand the process, and to figure out how to install them into a car that didn't come with them from the factory. This thread is the result of everything I've learned so far. By no means am I an expert, nor do I guarantee that what I offer here is 100% accurate. I've done a lot of searching, a lot of asking, and a lot of soldiering. With that disclaimer I present to you my findings.
Why would you even bother?
I feel old, I feel cold! But seriously, if you even have to ask, then don't waste your time.
How does it work?
It's just like having a rear defrost installed in your seat. Voltage flows through skinny wires which get hot due to resistance. It's a very basic system!
Is it hard?
Hard is a relative term, but if you can find 12v power, ground, and remove the seat covers, you can get some heat into your seats.
What seats can I add heat to?
Any! Subaru's been installing heated elements in seats for a LONG time. Heated seats are nothing more than a standard seat with a heating pad installed below the seat cover. Forester seats are no exception.
What do I need?
Where do I get the heated seat parts?
- Heated seat elements (the pads that go under the seat covers)
- Switches (to turn your heated seats on and off (even hi and lo)
- Heavy wire cutters (to remove the seat hog rings)
- Electrical tape
- Soldiering Iron (optional but recommended)
There are a few options here. You can buy a universal heated seat kit from an online auction website and install them. You could buy OEM heated seats and OEM heat switches. OR (my favorite) go to a junkyard and source the seat elements, switches, and wires from another Subaru. Heated seats were a standard feature in all winter package equipped Subarus. Your best bet is to check in a Legacy or Forester.
I sourced my seat elements, switches, and wires with plugs from a 1996 Legacy Outback with the winter package. Total cost for parts was $6.
The remainder of this how to will detail an install using factory components.
Gather your parts!
When pulling these parts from a junkyard, you can either take the whole seat and use it, or remove just the heat element (options will probably be determined by junkyard policy). I was able to take a razor knife to a pair of JY seats like a psycho ex girlfriend and cut out the elements. This is obviously the quick and dirty solution. The other option is to remove the entire seat skin by taking off the plastic clips. Straightforward to do - just remove all the clips and metal rings (called hog rings) until the heat element is exposed and free.
If going the psycho ex route, here's a seat roadmap to use so you don't cut the parts you need (note there may be a piece or two you will need to unclip to free the heat element even when cutting):
Try and remove the switches and seat harnesses as one piece if possible. Worst case scenario, get the switches and plugs, and run new wires between the two.
So I have a bunch of wires and 2 switches - now what?
There isn't much to wiring these in, as I mentioned. The relays are built into the switches. There are only 3 different wire inputs required to make these work
- 12v Switched Power
- Illuminiation (optional)
Factory Wiring Diagram:
Understanding the Diagram
Power- you can see that there's 12v coming in on a blue wire from the rear power supply relay. If you look at your Forester fuse panel, you'll see that it's already marked rear power supply/seat heater! You could also source power from the front 12v outlet as well.
Ground - There are about 6 ground wires that can be grouped together and grounded anywhere. Half are for the seats, the other half are for the illumination wiring
Illumination - There are two white and yellow wires for each switch that provide illumination power. In my opinion, it's unnecessary. The switches work and light up as normal without it wired in. Save yourself some headache and just ignore the wire.
Understanding the Switches
Not much to do here, the FSM explains it best:
What it all looks like
Heat Power wires
Heat ground wires. I grounded them out underneath the center console on the Ebrake plate
But wait, I'm still confused about sourcing power!
I simply spliced into the 12v wire that ran along the passenger side floor back to the plug in my Forester. Guess what color it is - that same fun blue! The arrow shows where I found the wire at:
Ok, I wired everything in, but one of the heating pads won't get hot. What did I do wrong?
Odds are everything is fine. If the switches amber light kicks on when you flip the switch you're getting power. Chances are the element has a broken wire. It's a very common issue in heated seats. Now you just need to track down the break!
So where do I start?
Take the element out and hold it up to a light so you can see the wires hiding inside:
My break happened to be surrounded by burnt wiring and was very easy to spot. I marked it with blue pen:
Cut into the pad with a razor knife to expose the wire. See the break?
Ok, found it. Now what?
Just add a short piece of wire to jumper the break back together. Either soldier or crimp and you're set.
That's the basics. I'll add more pictures of adding the seat elements to existing seats later. If there are any questions just ask!