You could be onto something, but I would suggest we try to jump to the relay and check for voltage to find out if we have an issue with the ignition switch.
Basically, all the switch needs to do is supply power on pin 86 of the relay.
So, remove the relay and turn the key and check for voltage here and if you have 12 volts then the ignition switch is fine.
Here is a guide that will help with this:
https://www.2carpros.com/articles/how-to-check-wiring
https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
If you have 12 volts here, then we need to jump over to pin 85 and check for ground. This is where I think the issue is.
Put your red meter lead on battery positive and the black on pin 85 and crank the engine. If your meter reads 12 volts then the PCM is grounding the relay and commanding it to close and start the engine.
If the PCM is not grounding it then this could be the PCM but more than likely you have an issue on the T41 circuit which is common on these vehicles. This is the transmission range sensor and tells the PCM that the vehicle is in park and is okay to start.
However, let's get to that once we prove this out and go from there. I attached the wiring diagram below so let me know what questions you have.
Thanks
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Thursday, February 10th, 2022 AT 4:09 PM