Hello,
I have a 2006 f150 xlt 5.4. I went out to fire her up and nothing happend.
It has sat for 6 days without being started. I hooked up my charger to it and a few funny things happened. One, the headlights and brake lights stayed on. No door open, no switch turned on no key in it. I also have a train horn on it and it has a compressor for the air supply. As the lights stayed on there was a faint sound of the compressor trying to air up to?? It is like there is constant power to the truck but the key is off and out. ( i also have remote start on it)
I thought it may be the relay for the lights but why would the air compressor sound like it was airing up too? I have disconnected the cables and left the charger on it for tonight. Any info would be GREAT.

 

Well, how is the compressor hooked up? Hook up a test light (goes between your battery and negative cable) and pull fuses until it goes out.

 

After charging the battery all night i hooked it up and she fired right up. Let her sit for about 10 hours and fired right up again. Lights are off, Compressor not running when shut off. Seems to have reset something i guess.