SENSOR ground (aka sensor return) or signal ground.
'Sensor Ground' it is Now ! In its 3rd revision
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While we are at this topic, can you explain a bit more.
If the 'sensor ground' wire is not attached to frame, where is it attached ? Is it the ECU pin 24 that act as 'sensor ground' ? If so, how does it act as ground ?
Also, it seems that 4 sensors - throttle position sensor, air manifold pressure sensor, engine temperature sensor and O2 sensor - are part of this 'sensor ground circuit'.
How does this grounding provide common reference for sensor output and perhaps reduce background electrical 'noise' or variation from sensor to sensor for more accurate reading ?