need to get out the ohmeter and start checking, sounds like a dead short somewhere, maybe you have the wires reversed on the gauge - and that would probably have killed the new gauge
"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