P0815 or P0816

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

No DTC P0826.
No DTCs P1825 or P1915.
The engine speed is between 500-7,500 rpm for at least 5 seconds.
The time since the last gear selector range change is greater than 6 seconds.