the sender works the way it works, there's no 'reversing' it ... some here say a 6V gauge will be fine on 12V, but it's recommended that a dropping ["runtz"] resistor be used, so yes, you may have fried the gauge using 12V
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
