A power system (10) includes a power source (12) having a power output (14) and a signal output (16) and is shiftable between an off state and an on state supplying a given power from the power output (14), the power source (12) producing a signal on the signal output (16) for a period of time when the power source (12) shifts from the off state to the on state and at least one component (18, 24) having a power input (20, 26) and a signal input (22, 28), the at least one component (18, 24) shifting to a diagnostic state when power at the power input (20, 26) rises from below the given power level to at least the given power level and a signal is present on the signal input (22, 28) and shifting to a second state when power at the power input (20, 26) rises from below the given power to at least the given power level and no signal is present on the signal input (22, 28).