Acura RL 2002 P0715 mainshaf speed sensor issue

[Vladimir Bugrin]

Hi guys
I have a P0715 issue on my Acura RL 2002
First I did the troubleshooting just as described in the electrical troubleshooting for this car. Both of the sensors mainshaft and countershaft showed in the between 400-600 ohm. Made sure the wires are not damaged or shorted to ground.
Even though sensor showed to be fine, I did change it. The P0715 still didn’t go away. I duplicated the wire from the new mainshaft sensor right to the ECU, and that didn’t help too.
Then I connected the oscilloscope to the sensor and as the car was gaining speed it showed pulses. But when the computer is connected to the OBD, it shows zero speed of the mainshaft. So I thought it means that the ECU is not seeing signal from the sensor and something might be wrong with ECU. But I doubt it because Acura’s ECUs are very reliable and think that the problem is not in the ECU
Since I live in Russia and this car is very rare here, there are no repair shops that know what else it can be.
If you could give me any hint what else should I do to get rid of this P0715 I would be the happiest person)

P.S. The issue might not came all of a sudden. I had to change the cylinder head gasket in the repair shop because the antifreeze was going to the manifold. So I think maybe they have did something wrong with the engine wires or else. But how this might cross with the transmission wires that they didn’t touch.. So the P0715 showed up while my first trip from the repair shop after I fix this broken gasket. Before the visit to the repair shop the automatic transmission worked perfectly.
I drive this car for 12 years. The mileage is 285 000k. Oil change in the transmission I did every 30 000k miles.

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