F150 Won't keep charge

I am having problems with my 97 F150 keeping it's charge. I have replaced the battery with a new one, took the alternator out and had it checked...it's fine, checked the ground on the starter & battery, checked the starter...it's fine, did the test light on the battery through the negative for every single fuse, changed the ignition starter switch, changed the starter solenoid. Nothing has helped. When I go to crank the truck nothing at all happens. no sound and no lights. It will run about 3 days on a charge. Here is what is happening though....The battery is still pulling a charge from somewhere...the meter read up to 0.34,(on the battery) key off, doors shut. Windows will only roll up & down when key is on accessory. It kept blowing the 15amp fuse, checked for shorted out wires and nothing. I found a semi disconnected GPS c-chip installed in my truck underneath my steering wheel column when I removed the panels. I'm assuming that the truck previously belonged to a rental car or leasing company. I traced the wires so that I could remove the c-chip completely. While tracing..I also found it connected through my factory radio wires down to some sort of audio/video device which helped support the c-chip, from there I traced the red wire to my passenger kick panel where it was connected in somehow with my FUEL RESET!...ARGGGG!!!! It was wired in to 2 12v relay switches that had the wires connected to the prongs! I cut the red wire and then pulled them from the relays completely. Truck cranked just fine (on charger) Then I just said to heck with it and pulled all the wires out of the relays which were Orions and not Ford Factory. Which were also connected to the main c-chip fuse box. Anyhow, I'm just ready to shoot this truck. I have a lot of money in it and it's in show room condition. But after pulling all the c-chip crap out it now reads 0.96 on the voltage meter. But if I also pull out my #21 fuse under the hood and my 2 interior accessory fuses below the dash it goes down to 0.01. I'm at a loss and am tired of trying to figure this out. Any help would be grately appreciated! Sorry so detailed. But at least it gives you an idea of what I'm going through...LOL. :banghead:

Yep, electrical problems can be a real pain in the rear. You're on the right track though. As you've done, it's a matter finding the circuit that's draining the battery. Pulling each fuse and then checking to see if the battery draw has reduced is usually the first step.

I had an auto repair shop years ago and electrical was one of our specialties. The shops will simply charge you their per-hour rate and do the same checking. We did discover common problems in the various cars that allowed for quick fixes though. One problem causing a drain-down in some cars was bleed-back current through a bad diode in the alternator rectifier, but I suppose that was checked when they tested your alternator.

One thing often needed is a wiring schematic (diagram). Check the Haynes books for your year/model, they usually have them in the last pages. You might need a magnifying glass to read parts of it. You should then be able to tell what fuse #21 is on and go from there. The same with the other fuses you mentioned.

One thing to remember is that there is usually always a small drain caused by radio clocks, the computer, alarm systems, etc.

Finding a mechanic who is good at this stuff is rare. If you get good at this, you could make some good bucks!

One nice thought about doing all of the replacements that you've done is that many of those parts wear out anyway, you've just beat them to the punch : )