So post #7 held the answer. This is very often the condition found at 3 post fuel gauges too.
Their engineers put a slither of metal on the back of that gauge to create the internal limiters ground path. Then so much more heat present = more part distortion, thus limiter operation fades.
A volt meter will show a minuscule amount of voltage continuity yet the needed amperage isn't conducted. Explains the disappearing pulse reading too.
Ohms measuring always tells the rest of the story. Happy moparing
