96 PU..The headlights will not shut off, unless the battery is disconnected or the 40 amp fuse from the distribution panel under the hood is removed. Removing the light switch and disconnecting it from the wiring harness still will not shut off the lights. Any suggestions?

 

look in your power distribution center and locate the headlight relay it may be bad. Causing it to stay on all the time. Distrobution center is the box with all the fuses and relays under the hood. Pull the relay and see if light go out.

 

Any chance this is a Canadian truck with Daytime Running Lights?
Is the Hi beam indicator dimly lit?
If so replace the DRL module on the drivers fender well (Black box approx 3x4. probably smoking hot)

 

what if this doesn't work

 

Then you need to figure out where the short is.