i have a 2013 dodge ram 1500, the drivers side headlight only stays on for 15 - 20 seconds then goes out ,, turn the lights off and on again the same happends, help

It is so new and that is so strange, you must go see your dealer if the power or ground are lost to the headlamp bulb after 15 seconds. You can trade bulbs left to right and see if you have a weak filament it would follow to the other side. But issues of this type that are not found with inspection only, they can be widely known and time can be saved with any wiring update or correction they might have. Newer cars have DRL modules for headlamp illumination and the wiring is busier. It used to be the left and right were wired separate, fused separate and or had breakers. The switch of power was protected by a thermal limiter to cool them down and reset as necessary to operate the circuit, but cause an open temporarily for time of trouble. you would lose both, and all others then. See if the dealer knows already and has a fix ? or you just have the filament at fault.

Further diagnosis requires wiring diagram for identifying all the components in the system and how they relate. You would need a 12v test light and a DVOM most likely. Inspect the components, their connectors and fully operate all the components and note any other symptoms that may relate. Some vehicles have headlight relays and simple substitution or trading parts can make the problem go to the other side of your truck, try that after the headlight bulb swap as a quick test.