as Andrew says, the engine won't run if the resistor is 'burned out', but if the wiring is correct, a bad resistor will show up as: trucks starts fine, dies as soon as you let off the starter
"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