Greetings All I've been driving a 2010 Prius for almost four years now. I love this car. A real solid everyday driver. Mechanically could not be better. A few days ago I experienced a very odd situation. My drivers seat started a heat cycle as if I turn the seat warmer on... however, I don't have heated seats. The switch location (next to the round power outlet) is blanked. I've assumed it was spec'd without seat heaters. Now I not so sure. I originally suspected the heat was somehow coming up from the floorboard but that's not the case. The floor is cool, the seat bottom and back is hot (almost uncomfortably so). The heat cycles off after 5 or 10 minutes then back on again after it cools. There is a silver box under the seat. I've assumed this is related to audio or GPS. Tonight I noticed a wire (about the diameter of coax cable) running up the back of the seat from the nest of wiring at the silver box. I haven't removed the seat or dissected the wiring (yet). Does anyone have an idea what I'm dealing with here? Thanks, Dave.
I’m not sure, either: according to the sales brochure for the 2010 Prius (PDF), trim level IV included “Leather-trimmed seats and steering wheel with driver's seat power lumbar support and heated front seats with bottle holders in front doors” (emphasis added) as standard equipment. Might a previous owner have removed the seat heater switch (YouTube video), for whatever reason? The box is probably the Stereo Component Tuner Assembly, i.e., the SiriusXM satellite radio receiver, part number 86180-50300. The cable might be for the Front Lumbar Support Motor Assembly LH, if your car has the power lumbar support, but I wouldn’t expect this to be a source of much heat. Can you post some photographs? Also, does your car have fuses installed in the SEAT HTR FL or SEAT HTR FR positions in the Instrument Panel Junction Block Assembly, and if so, what happens if you remove them?
I was going with aftermarket heated seats. Look around the seat for an out-of-place on/off switch. However, if you have IV, it did come with heated front seats and they do cycle on/off as you described. It's possible the previous owner took out the switch (for whatever reason). Maybe they wanted an aftermarket slip-on cover and didn't want the seat heaters setting it on fire.
That would bother me enough to have to tear into the seat to find out -- as much as I would hate to do it.