My seat heaters took 4 trips and 2 different dealerships, they finally got it right and they have been working correctly for the last month, longest time so far. The drivers side back was always giving me trouble and never worked correctly, but so far it has been working ok. The bottom and back seat heater should heat up at the same time and about the same temperature, mine are pretty even now. and the passenger side seat heaters also heat up at the same time and same temperature when turned on. I forgot to add, the last trip for the seat heater issue took 2 weeks, while they ordered parts-