Last week I went to work and got a call that my trucks lights were on. Thought it weird, but sure enough with the key off and headlight switch off they were on. Jumped the truck and couldn't get them to turn off, so I had to pull the battery cables to kill the power. Since then its been flaky, sometimes they turn off sometimes not, sometimes while driving they'll go out but markers and turns remain. I noticed yesterday that the glove box had water in it. Got me thinking (besides that I need to get the windshield seal repaired apparently) so I did a little recon and I think the daytime running lights module is over there somewhere, I pulled out the glove box and I didn't see it, anyone have any idea where the heck on a 01 Superduty that thing is? Yeah the relays are good under the hood, and NO those aren't all there is to daytime running lights, there is actually a module that controls them and the headlights apparently and it must be shorting out to cut the lights in and out. Any help is appreciated.

 

Should be behind the drivers side headlight.

 

in the fuse panel under the hood on the driver side there is a fuse for the DTRL and the fog lamps.

 

Its in front of the drivers side battery attached to the header panel. Like module protected by a cage looking thing. The plug comes right up in the bottom. Just unplug that. You could pull the fuse if you don't have fog lights but Im assuming your 01 has them.