Quote:
Originally Posted by 87m491
Bentley says one of the crank sensors is for factory tech diagnosis. The fact that I'm getting power to FP during cranking tells me the other sensor is OK.
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No, the TDC sensor referred to by the Bentley is on top of the engine case and is not one of the two flywheel sensors. It is indeed only used at factory and never used afterwards.
As I said before, the two flywheel sensors, those that are attached to the same bracket on the upper left of engine, are sending proper engine speed and ref position signals to the ECU. If one of those signals is failing to be received at startup, the ECU does not keep power to the FP. Again, during cranking, power is always sent to the FP no matter the sensors.
The sensors are in no way a condition for sending power to the FP during cranking. They become indeed a condition once you release the ignition key. The ECU senses this by seeing an engine speed of at least 200 rpm at the speed sensor. But for this, it must see this signal as well as the ref signal at startup (the ref signal becomes less indispensable once the engine is running).