I hope somebody can help me. Last night when getting into my truck it would not start. I always have the headlight switch set to the automatic on (autolamp) position. When I tried to start the truck it wouldn't start up. I made sure the gear selector was in park and started fumbling around with the headlight switch in case I had a dead battery and noticed it would start fine when the headlights were in the off position . After the truck started I turned the lights on in regular mode and it shut down the engine!!! I then tried every putting the switch in every imaginable position and the truck would only start or run when the switch was off.

Out of frustration I started to drive the truck on a well lit road for a few hundred feet until I had to turn onto an unlit street. While driving I turned on the headlights and this time it didn't shut the engine off. I didn't dare mess with the switch again until I got home. Everthing worked fine until the same problem happened again this morning when getting ready to drive to work. It's a no crank - no start situation. As a matter of fact, If I turn on the headlamps or parking lights while driving the truck shuts off (stalls).

If anyone has a clue as to what might be happening (or know somebody who has had this happen) I would be thankful.

 

Have your battery load tested and the alternator checked. To sum it up, your battery is weak and the headlights use enough amperage to kill the engine.

 

A similar problem happened to my buddy with a 7.3 Powerstroke. He added an Edge programmer, and whenever he turned on his wipers, the CEL came on and the truck would stumble and eventually die. The chip was replaced and it runs great now...