Starter keeps cranking after engine starts

[Shadow351]

Lately I've been encountering this intermittent issue where the starter remains engaged and keeps cranking for a few seconds after the engine starts. I have confirmed with a test light that when this occurs, the 'S' or trigger terminal on the starter is energized so it is not the starter solenoid sticking. I have also swapped the starter relay for a new one and the issue continues. based on the wiring diagram this seems to indicate that the the PCM is keeping the starter engaged for a couple seconds after the engine starts. I'm assuming there's a wonky sensor that is causing the PCM to do this but there are no related codes set so I'm not sure where to continue troubleshooting. Has anyone else encountered this and found a solution?
Thanks

 

[Axle]

Lately I've been encountering this intermittent issue where the starter remains engaged and keeps cranking for a few seconds after the engine starts. I have confirmed with a test light that when this occurs, the 'S' or trigger terminal on the starter is energized so it is not the starter solenoid sticking. I have also swapped the starter relay for a new one and the issue continues. based on the wiring diagram this seems to indicate that the the PCM is keeping the starter engaged for a couple seconds after the engine starts. I'm assuming there's a wonky sensor that is causing the PCM to do this but there are no related codes set so I'm not sure where to continue troubleshooting. Has anyone else encountered this and found a solution?
Thanks

If you have eliminated the starter solenoid and the starter relay. Then the problem is somewhere in the Logic. You will likely need someone to look at the ECM logic to see what is holding the circuit closed. You may be correct that a sensor is holding that circuit closed. Unfortunately, manufacturers don't just give out diagrams on the circuit logic.
If I made a guess. I would think it's something to do with the sensor that looks at RPM or crank position.

 

[Shadow351]

Yea, Unfortunately, the factory troubleshooting guide lumps 'One-Touch Integrated Start (OTIS) does not operate correctly' into a single troubleshooting tree and almost every branch ends with "Install a new PCM" (So they don't differentiate between a No crank, a long crank, continues cranking after engine is running, etc.)

I thought maybe crank position sensor, but then i would expect a crank no start because in order to fire injectors/coils the PCM would need to know crank position. I know on some vehicles you can watch the tach during cranking to check if the crank pos sensor is working, but annoyingly, these cars do a gauge sweep on startup, and the gauge sweep doesn't even start until the engine is already running.

I've tried logging data with my Autel and ForScan, but the issue is so intermittent, that every time I've spent the time to set everything up, the issue hasn't occurred.