remember that even sitting still, with the engine running there will be at least fine vibration felt thru the entire truck, enough to cause poor [oxidized] connections to become randomly intermittent
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics