There's a dash gauge voltage regulator required for MoPar's. Take a look at Rock Auto Parts - they're about 35-38 bucks for the good Standard branded item. If they fail, you will have gauge and sender problems - or at least on a Ford it will.

RockAuto Parts Catalog

"STANDARD MOTOR PRODUCTS Part # VRC601 More Information About this Part {Click Info Link for Alternate/OEM Part Numbers} 12 v to 6 v Voltage Reducer for the Instrument Cluster Dimming; 12 Volt; Contents: Regulator
w/o Rally Package"

I had this typed up and my ISP evidently crashed and I never got back to it