when the truck is at idle and even driving the lights pulse what could this be is it a common problem???

 

clean your ground wires and make sure there all connected that should fix the problem i relocated the one that goes from the battery to the side of the truck down on the frame

 

Mine also did that and turns out there was a bad connection in the input wire that goes to voltage regulator.

 

definitly check all yoour ground wires i had the same issue with my truck but i also had a short under the dash that was blowing fusible links it was a nightmare but yea i would definitly check all your ground wires and make sure there all tight cause these old trucks are rattle boxes

 

My truck is doing the same thing so if you figure out what it is let us know because I have checked every thing and I still can't find so good luck.

 

mine was the voltage regulator. eventually it went and i was stuck on the side of the road.

 

mine did that too and when the voltage regulator went i was a few hundred miles from home and poked and prodded around with the alternator till it was charging (by grounding one of the terminals on the alternator) but it bypassed the regulator almost got home before it let the smoke out of the hole electrical system (whoops) so I guess Its time to swap the motor into a better truck