No start by key,but works when jumped.Help!!

The amp gauge is in the instrument panel. Mopars with an amp meter (not a
volt meter) run all accessory current through the gauge in the dash. If you have a 50 amp alternator and it's charging at maximum output you have 50 amps going from the engine compartment through the bulkhead connector
(where all the wires enter the passenger compartment {by the master cylinder}) and then through the charge gauge on the instrument cluster.
toolman