How many of us are there? Owners of Dodge based RV's?

Griff,

Wow, I didn't know there were 5vdc gauges. If someone hooked up the positive wire directly, then it would explain the gauge maxing out quickly as the voltage exceeds 5vdc.

Eyeteeth,

So, you just need to measure the voltage at the gauge to see if it exceeds 5vdc when the engine has warmed up. Actually, it should be reading about 2.5vdc when the engine is warmed up (assuming it is a 5vdc gauge).

Anxious to hear what you find.