Code P0717

I am having the same issue as the OP was having, with the trans (4T45E) hunting for gears etc. (2009 Cobalt Lt 2.2L)
I did all the test posted using the J44152 jumper harness and everything checked out in spec, so the Diag sheet said to replace the TCM.
I replaced the TCM with a reman unit using the VIN, with the new TCM, it now shifts fine even after multiple engine stop restarts on test drives, it would always turn on the CEL after the 2nd start up and start hunting for gears, now the CEL light still comes on setting the P0717 code but it no longer hunts for gears.
Now with the very limited use of a Pro scanner, the transmission live data still shows the same ISS drop out below around a 1,000 RPMS with both TCM's, but when I use a DVOM to check the voltage output of the ISS straight off the jumper harness (I did this before and after TCM replacement), the voltage values go up smoothly and back down smoothly with the engine RPMs, but the scanner is still showing the same ISS dropping out. Is it possible to have a bad ECM that is not picking up the ISS reference voltage from the TCM and displaying it on the scanners live data and setting the code P0717?

I know I could have gotten a defective new TCM, but it is a different TCM (I kept the old one) with the same (only one) transmission code set, but with no symptoms with the new one, meaning if the light did not come on, you would not know anything was wrong.

Hope someone can help out with this.

Okay, I have not replaced the PCM Yet (new TCM still), transmission still feels normal, but on live data (I am using a much cheaper scanner this time) at idle in park the TCC slip speed is 678ish RPMS (vey close to engine RPMS), and it goes up and down as it should when giving it gas and letting off, but the ISS is 0 RPMS no matter the engine RPM in park, power torque the engine in drive up to about 1700ish RPMS and the TCC reads normal, but the ISS is still showing 0 RPMS.
Now put it in drive or reverse, and once the VSS shows 2 MPH (car moving) the output speed sensor starts showing the RPMS (normal) and the ISS starts showing RPMS above about 350-380 RPMS, then everything looks normal, the TCC applies and the TCC slip speed RPMS drop to about 14 RPM (normal) (and I ran out of road, testing), but when I let off the gas and apply the brakes the TCC slip speed goes crazy, up to 8100+ RPMS and back down again to normal, then while coming to a stop (every time), the ISS right about 350-380 RPMS and at about 2 MPH the ISS drops off back to 0 RPMS, TCC slip speed still normal 670ish RPMS.
And since the TCC slip speed looks normal (mostly) but the ISS doesn't show any RPMS until the car is moving above 2 MPH, does this confirm the PCM requires replacing?

If the TCC Slip Speed RPMS are correct and the trans is shifting correctly now, how can the ISS reading not be correct?

Doesn't the TCC Slip Speed get it's info from the ISS to calculate the TCC Slip Speed RPMS?

Yes, the P0717 code will not go away, I'm guessing because the scanner shows no ISS signal, but I'm guessing the TCM can read the signal OK and that is why it still shifts normal, lock up and all.

That makes since about the crazy TCC slip numbers, thanks.

So I am taking it you still think this is a PCM issue and not a defective new TCM issue or ISS/harness issue?
The PCM is not reading the TCM correctly then, therefor setting the P0717 code?

Thank you for all your help on this BTW.

Isn't that what I did using the J44152 jumper harness and testing the circuit/system in the image below? That is why I replaced the TCM, and by replacing the TCM, it corrected all the transmission shifting issues, but the P0717 code keeps coming back.

Do you happen to have the wiring schematic between the TCM and the PCM, above post is only of the TCM and related items. I don't see anything dealing with the PCM wiring, other than the 4 (tan and tan, black) Data Bus wires pointing to the computer data lines system. Is that the wires you are meaning to test? And if the ISS wires only show going from the sensor to the TCM, how would I test from the ISS sensor to the PCM?