I'm building an ECU from scratch to plug into a factory wiring harness on my LTD LX. In the EVTM it shows the ground for the oxygen sensor heater going into the ECU. Does anybody know off hand what the ECU does with this ground? I assume it either opens it when the sensor is warm or there is a current shunt to indicate a faulty heater.
What's interesting is that, according to the "EEC Bible" other vehicles had the heater permanently grounded outside of the ECU so it is always on. Is there any reason to turn off the heater once things are warmed up? I still have a couple unused pins on the microcontroller so it wouldn't be too hard to add in that function if it serves any advantage.
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