2008 Saturn Vue P0606 Fault: Symptoms, Diagnosis, and PCM Replacement Discussion

2008 Saturn Vue, 40,000 miles, V6, automatic transmission. Recently encountered the P0606 diagnostic trouble code three times. Approximately six weeks ago, the vehicle exhibited a rough idle, misfiring, and pinging sound, making it difficult to start. After scanning the system, a P0606 code was retrieved — indicating a fault in the Powertrain Control Module (PCM) processor. I attempted multiple starts with no improvement. The issue persisted even after clearing the code. My wife reported the same symptoms recently; she took it to the dealer, who cleared the code and claimed that if the problem recurs, they will need to replace the PCM. Three days later, I tried starting the vehicle again — the issue returned. After clearing the code, the car started normally. A key observation: when turning the ignition key to 'ON', all indicators appear normal. However, when attempting to turn it to 'START,' there is no click or crank — the engine does not respond at all. When I turned the key back to 'OFF' and then to 'START,' the vehicle started successfully, but the P06006 code reappeared. I am wondering if this could be related to a mechanical issue with the rod connecting the ignition switch to the contact switch located at the base of the steering column. In the 1970s, I experienced a similar problem where a faulty contact switch prevented engine start — I resolved it by installing a dash-mounted start button. Could a power supply contact to the PCM be intermittently failing, leading to the P0606 code and starting issues? Is this a known issue in 2008 Saturn Vue models? Any insights or diagnostic steps would be greatly appreciated.