I have a 2006 F-150 Lariat Supercrew 4x4 that has been having a dead battery problem. I have gone through the voltmeter fuse test, and found a draw on fuse number 40 (Low Beam Headlamps DRL). I pulled the fuse and have the battery hooked up to the charger now. My question is…. What could cause this problem? I have an aftermarket radio and amps. I also have a camper shell on the back. At first I thought it might be one of those causing problems, so I disconnected them from the system and still had a dead battery overnight. Yep she goes dead in hours. BTW she a brand new battery installed after the problems started. No changes to headlights all stock as is the wiring to the headlights, no splices ect. When I pull the fuse the draw drops off. The first thing that clued me into the headlights was I had her parked in the driveway and when I took the trash out one night the headlight where on and very dim. Is this a DLR problem, battery saver issue, or just a short that developed??? Any help would be appreciated. Can’t drive to the store without worrying she might not start again.

 

Certainly does sound like a headlight problem, doesn't it?

You have the "autoheadlight" option, don't you? What happens if you turn it off? I'm really thinking it's something in the headlight shutoff delay that takes place after you turn the engine off. The simple circuit diagram in my Haynes Manual doesn't show the control circuit for this, but that's where I'd look first.

The DRL's should also be off if the parking brake is applied, I believe. Does applying the parking brake get rid of the draw? This might rule out the DRL circuit being at fault. But, I can't see why they'd stay on with the engine off.

- Jack

 

The parking brake has been applied in the past. I have the fuse pulled and finished charging the battery. I am leaving the fuse out tonight. If I dont have a dead battery after 12hrs, at least I know where the problems is located kinda LOL.

 

And, the Autoheadlight position of the headlight switch?

- Jack