Battery draining

if the battery is not bad...wont hold the charge...to to how to test ,connect test light or volt meter to your battery ..its best to pull on fuse at a time and check reading if it drops thats the circuit with the draw >>>> https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

First thing I would do is fully charge the battery and then disconnect the battery cable overnight to see if it still dies. If it goes dead, that would be an internal battery short, common in batteries older than five years. Next suspect is alternator with "leaky" shorted diode.

follow the instructions for parasitic drain before you do it . Get a multi meter , if you want to do your own repairs there are tools you will need . See if the batt has 12.5 volts , see if you can find a date of purchase on it .Start the car there should be 14+ volts at the batt if the alt is good . a batt charger can indicate the condition of the batt. or if it will accept a charge . That trucks pretty old there could be wiring issues , mice will invade even a daily driver .