2011 Volt Premier (0737); 2010 Highlander Hybrid; 1993 K3500 6.5TD former ambulance
Thanks for your thoughts. BECM certainly could be the problem, since I think it's ultimately making the "decisions" on when to allow battery use. Those decisions seem increasing random lately. For example, yesterday I moved the Volt out of the driveway and parked it on the street. It was 40 degrees F (about 5 C) ambient. When I pressed the start button, the DIC showed the gas gauge and had the fully charged HV battery grayed out with 20 miles range indicated. Yet the ICE did not run at all. It was battery propulsion for the entire "trip" out to the street. MGV showed the ICE at 37 degrees F and the HV battery at at 52F. Since the battery temperature was higher than ambient, I presume the HV battery heater is at least marginally working. MGV indicated battery was outputting 1.2 amps at 386V (463 watts) while sitting in the street.i run my volt in -40 weather and have no trouble with my gen 2 other than the cabin heater
when engine running due to temperature, motor runs a lot off and on keeping the motor temp between 64c and 53c even when it has battery
sound to me like your heater for your traction battery is dead
other posts have said that it starts to work at 16c and colder
so if your hv/traction battery is cold the car does not want to make it available
your engine when it comes time to use the extra power from the battery is denied the engine has to run harder and give you bad fuel mileage and your battery doesnt drop
so - heater or module that controls it and i think thats the becm
thats my guess
Seems like the BECM doesn't want to let the HV battery output the power needed for typical driving demands, so it's indicating via the DIC that it's in ICE mode, even though the HV battery is providing the initial low-power needs. Put another way, it's as if the BECM wants to use the entire available HV battery capacity as it normally uses the low-end buffer. The driver experience is like driving a spastic Prius.
Thanks again. All guesses are welcome!