Tom A prime place to look would be under the cab where the bundle of four wires transition from the stationary frame of the combine to the hinging area of the feeder housing. The wires can break here over time from the repeated flexing and short out. Gamaman
Tom My first suggestion should have been to turn the header height selector switch to off and see if that stopped the malfunction. If it did, then trying the different switch settings of low med and hi could help you narrow down the short.