I have an 02 f150 fx4 super cab. my truck has started to not crank erratically. when it want crank the theft light blinks fast. the truck turns over but want start. if I let it sit or try the next day it cranks fine. recently it cranked one evening then the next morning nothing. its almost like it wont crank after a rain or heavy dew. im getting ready to take it to the dealership, but am concerned that they wont be able to fix it if its working fine while its there. any advice or can they look back into the ecm to see what the prob was when it happened. also when it doesn't crank the dash lights, radio, ect. work fine. thanks in advance.

 

Disconnect the battery for 10 minutes. Then try it. The PATS module could be bad but I'm not sure how likely that problem is.

I'm not aware of a starter/fuel pump interrupt for the F150's but there could be.

 

Anybody else? Can a weak battery cause pats issues? Once I get it to rank it runs fine, and never stops till I try and start up again.

 

You have a GEM issue caused by a leaky windshield. You need to get the Windshield resealed. Water drips onto the GEM and fuse box, causes corrosion and the issues you described. The GEM controls pats and other things.

You might get lucky and after the reseal/no rain for awhile, the gem may dry out enough to function correctly. Otherwise the dealership can replace it. ~$800.