got a head scratcher...

The battery will drain down to 3volts over a wknd if I let it sit. Have to jump start it after that.
97 f-150, 4.6 2wd
Started experimenting...
Took a good battery and connected the hot wire and just touched the ground and listened. A relay was clicking every time I would touch the terminal. got to checking which one, and it is in the small panel behind the "power distribution block" on the drivers fenderwell. It is the only relay there. The others are circuit breakers.

Any Idea what switch is sticking closed to keep this relay energized when the ignition is off and the key out?

Help!!! My truck is dead and useless until I fix this.

 

BTW, no auto headlights, aftermkt radio, fog lights. Pretty much stock. Shouldn't the only thing be using power while the truck is off be the radio clock and the computer memory?

 

my truck wouldn't hold a charge either and it turned out to be a bad ground and a new alternator. cleaning the battery turnminals and the connectors that connect to the wires isn't a bad idea either. if you do that, mix up some baking soda in some water and let the wires and the terminal connectors soke. also using less water and making a paste works well too. you just wanna get rid of as much corrotion as possible.

 

Found out yesterday that the offending relay is the "battery charge relay" for the trailer wiring. Removed the relay and it seems to be fine.

I figured it out by asking the auto parts place to give me a list of relays available for my truck. With this relay removed, all other "relay-ed" items worked, and this is the only one that didn't affect the function of the truck, plus this was the only one on their list that matched my symptoms.

 

Thanks erinspeed. I have an '00 f150 supercab that all of the sudden was draining the battery after a new trailer wiring harness was put in. I tried removing the relay and will keep you posted if the truck will start later this morning.( it usually only took a few hours to drain the battery to where it wouldn't crank over)