Won't start on 1997 Ford Expedition

The battery in my Expedition has been replaced 3 times in three weeks....after the vehicle sets for a couple days it will not start. The Ford dealership repair shop can not find the problem. I am at a loss what to do next.

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2 answers 1 comment
THE MOST LIKELY CAUSE IS ELECTRICAL DRAW. REMOVE THE NEG BATTERY CABLE, PUT A TEST LIGHT BETWEEN TH NEG POST AND THE NOW LOSE TERMINAL. IF THE LIGHT ILLUMINATES BRIGHTLY, THERE IS A DRAW. (A SMALL AMOUNT OF LIGHT CAN BE PRESENT FOR FULL-TIME CIRCUITS AND PCM CONSTANT VOLTAGE)
UNPLUG FUSES ONE AT A TIME UNTIL LIGHT GOES OUT. WHEN YOU FIND THE FUSE WITH THE DRAW YOU'LL HAVE TO TRACE WIRES AND/OR
REPLACE THE NESECCARY COMPONENT LINKED TO THAT FUSE.
Thank you so much. I would think the Ford dealership would have done this but it would not surprise me if they didn't. I will find someone to do this test for me and will let you know if it worked.
did you have your alternator checked???? and did they go over the ALL THE GROUNDS in your truck. most cases they check the main ground where as this truck has 4