Gauge is just a gauge - single 0-5VDC input from EEC(200/200) or TSCU(100) drives digital and analogue indications.
TSCU, ECU/EEC control the autofeather.
There is a time delay from loss of signal until feather - supposed to account for transient loss of torque signal. (during the test, drop the switch, uptrim light, 2 3 feather)
But autofeather with loss of sensed torque only (ie engine still operating) is almost always the TSCU getting upset.