Inverter functions perfectly when not towing. Factory wiring, under warranty. I am suspecting the electric brakes and the system will charge the trailer house battery while driving may put a bit of a strain on the alt. trying to use the inverter. May be a "safety" so too many amps are not drawn through the system.
I have the same issue. Was towing my travel trailer and could not charge my daughters DVD player. I also cannot run my electric shaver off the inverter...(sounds funny, but i shave in the truck on the way to work when i sleep in!LOL)...but the inverter in my old '07 Caliber R/T would run it no prob. I think it is just a weak sh*tty inverter.