Hi,
It could be a few things. First, when it won't start, see if it does in neutral. If there is no change, the next thing I would recommend is checking the starter relay. It may be failing.
If there is a different relay having the same part number in the fuse box, switch them. If there isn't, here is a link that explains how to test it:
https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
If that is good, we need to check the relay circuit to see if there is power to it as well as a ground path via the PCM. This vehicle has a totally integrated power distribution module (TIPM). They are known to have connector issues, so leave the key alone for now. Chances are that isn't the issue and yes, it needs to be programmed.
I attached the wiring schematic for the starter circuit below, so you have a reference.
Let me know what you find.
Take care,
joe
See pic below.
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Saturday, August 19th, 2023 AT 10:46 PM