seat heater not working in hybrid mode

looking4warmth

My seat heater works fine in gas mode, but shuts off the minute the car enters electric mode. Once it goes back into gas mode, I can put the seat heater right back on. Any thoughts about what might be the problem?

thecardoc3

There is no way to just say off-hand exactly what is wrong, what you need is someone with the correct tools and knowledge to investigate system's operation. Consider that in electric only mode the hybrid control ECU might be setting a limit on how much of a load the hybrid battery system is allowed to put on the battery. In order to provide as much energy as possible to propel the vehicle, some loads might need to be shed. Heated seats aren't necessary so it would make sense that the SJB (smart junction box aka BCM) would shut them down. There are other systems that might also be getting limited or shut down if the system is shedding loads. (rear defogger, blower speed except for when on the defrost setting etc)

That essentially sets the initial phase of the diagnostics, the next step is to pull codes from every module in the vehicle and then directly observe and investigate the heated seat system operation and see what if any system data provides any clues as to why the HVAC controller, SJB, DC/DC convertor, and/or Hybrid ECU might be commanding reduced power mode.