Headlights killing the Engine

[Super Diesel]

Hey guys,

I'm posting this for the guy that bought my 7.3. The truck is a 2001 w/ 173k miles. He sent me a text this morning asking me if I knew what was wrong (I know that I'm under no obligation to help, but that's not how I am), here's the synopsis...

He parked the truck on a declined driveway (front of truck is pointing down) when he had less than a 1/4 tank. The truck stayed parked there for a few hours. When it was time to leave, the truck thought it was almost out of gas and died on him. After letting it sit on level ground, the truck re-established the correct fuel levels and drove perfect.

Since then (about a week ago) the truck has been doing something really weird. Whenever he turns the headlights OFF, the truck turns off. The truck starts and runs fine, just does this thing every now and then. Not all the time.

I'm not sure what the problem could be, and it's kinda hard to use the search function to diagnosis this problem - but I tried anyway. What I got was:

Maybe a loose ground somewhere, a weak injector switch, possible bad alternator, disconnect both batteries and run the juice out - then hook everything back up (see if that kills the bug in the system), and other things I don't believe to be the problem (fuel tank related).

What do you guys think?

[ToMang07]

Does it have a DP Tuner on it? HID's?

[Super Diesel]

No, nothing. No chip, no HIDs. It DOES have the 05-07 headlights though... could that be a reason?

[ToMang07]

Originally Posted by Super Diesel

No, nothing. No chip, no HIDs. It DOES have the 05-07 headlights though... could that be a reason?

I don't know.... my thought was a DP tuner causes electric interference with some stuff, like stereos and HIDs that can cause it to stall out. Maybe a CPS?

[Super Diesel]

Originally Posted by ToMang07

I don't know.... my thought was a DP tuner causes electric interference with some stuff, like stereos and HIDs that can cause it to stall out. Maybe a CPS?

Nah, I don't think it's the CPS. It was just replaced (or it was supposed to be) about a month ago. I have no clue. Would this problem even throw a code at all?

[azkcr]

I don't know what the heck is going on with the headlights.

About 2 months ago, our 7.3l would take forever to start and if you got the RPMs about 1,200 or above it would die.
I started it and let it idle for over 20minutes and it has start and runs great since.

Electricity is freaking WEIRD in PSDs IMO. There's a lot of stuff that can go bonkers when your batteries are low, or nearing the end of their useful life.

[Super Diesel]

Dang... well, I just replaced the batteries too. Probably about a year ago now. Damn, I'm stumped as to what the issue is...

Thanks for the brainstorming though. At least I know peeps are trying to help out! And I agree, electricity is freaking weird in these trucks...

[Chakir]

My truck is parked the same way, and yea the gas gauge registers lower than actual. I've never noticed that having any adverse affect on anything, tho I've never had it run out.

I've read on here that the windshield can be prone to leaking, is it plausible that some water is behind the dash doing something?