I have an 07 Prius Touring that I had leather and heated seats installed aftermarket. My seat heaters have never worked correctly. They either work intermittantly, or just the high works (not the low) or just the low works (not the high) or they don't work at all. Sometimes the seat heater light is on, but the switch is in the "off" position. I have had it back in to the place that installed them and have had the relay replaced, the actual heaters replaced, and this last time, they replaced the whole thing - installed a different brand and everything. Has anyone else had issues like this? Any suggestions? Please help!
Were you bad in a past life? If the thing is getting 12V, and you've replaced everything, there isn't much more to say. Bad Karma!
My '98 Saab had seat heaters; when they were working I loved them. But they broke about every other year, and eventually I stopped paying to have them repaired. I think the issue is just metal fatigue. You're temperature cycling the resistor wires between cold and hot, and applying repetitive mechanical stress as well every time you sit down, get out, shift position, etc. The wires just break eventually and you need to tear the seat apart and put in a new heating pad.
Sorry to hear about your trouble. I think your 98 Saab (most Saabs around that time) was known for its electrical problems. I have a 95 Volvo that has had lots of electrical and other problems. Oddly, the front seat heaters are about the only thing on it that have never failed.