my battery on my 2003 expedition is draining over night. i just got a new battery thinking it was bad. i also found that relay #203 is getting way to hot. i tested if i had a short with a test light and i found out if i take the wiring harness off with the clip you have to pull up on the fuse blox the light turns off. i have no idea what that harness is for. can any one help me?

 

Do you have any extra stuff on your truck??? Like non stock radio,, extra lights,, or anything electric thats not stock??? My guess is that harness is the power supply for the fuse box??? Also might want to find out what that relay is for ???