I just successfully completed a repair of both the seat bottom and seat back heater elements on a 98 Outback Ltd (leather seats). It was not an easy or quick job - but a freezing derriere soon became enough motivation to get down and do some fixing. Here's what I learned and some useful tips:
1. First check that you are getting voltage at the connector underneath the seat. The voltage is switched between one of two contacts depending upon the high or low setting.
2. If there is no power to the seats - Check for a failed or sticky relay (passenger footwell by the front door jamb). This was a problem I encountered several years ago now - and had to replace the relay. This relay provides power to the heated seats with the ignition key in Acc/Run.
3. If you are getting voltage at the connector underneath the seat (and it correctly switches between the pins based upon the hi/lo setting) - then its time to pull the seat out.
4. Once out - dismantle the fore/after lever and separate the seat into the the base unit and the back.
5. For the seat base - undo the plastic retaining clips all the way around the seat. You will need to push down on the seat to compress the foam and provide enough slack to unhitch the clips.
6. Hog Rings are used to secure the seat cover to rods embedded in the seat cushion - cut the hog rings with cutters (and be sure to remove all shards - they are very sharp).
7. Check for continuity on the main element circuit in the base (be sure to test for continuity without having the thermostats in series with the tester). To get at the thermostat soldered connections you will need a knife or sharp pick to remote any blanket/adhesive. The rear part of the heater blanket is made in a sandwich with double-sided tape holding the sandwich together. I discovered several 'hotspots' where the heater element clearly got hotter than it should - and had singed the foam and the heater blanket material. These are the most likely spots for a break. Also, and here's the kicker, the breaks won't necessarily be visible - because the heater wire is encased in a thin, very tough insulation - and one of the breaks wasn't directly visible because the wire had broken while leaving the insulation intact. It was only by gently bending the wire into a tight radius that it was apparent that the heater wire inside had separated. It is possible to localize these breaks, strip the insulation back, solder the break (preferably twist the two ends together and then solder). Once soldered, I used high-temp silicone to dab on some insulation. The rods embedded in the seat bottom foam had started to separate and pull out in a couple of places - I used superglue to repair those areas and embed the retaining rods firmly back into the foam.
I repeated this process on the seat back - that also had a separate break in it.
Instead of using new Hog Rings - per the link provided to scoobymods - you can use zip ties to tie the seat cushion back down to the base. Then reassemble everything and enjoy the warmth.
So, why go to all this trouble? - well the aftermarket seat heater kits cannot be used in many vehicles that have leather seats. In the OB Ltd seats there are three retaining rods holding the seat cover down to the seat cushion and the one in the middle of the seat (running fore/aft) is the real problem - because it prevents you from using the replacement heater pads which presume that you can use the entire bottom surface (this is not a problem for the cloth seats as far as I'm aware). So I thought I would have one last go at getting the elements back up and working (and all this presuming you don't want to drop $$$ on a new heater blanket - assuming those are available as a separate part)
