Many newer GMs have a starter system that is controlled by the BCM and ECM. Basically you turn the key and the BCM tells the starter to crank until the engine starts. You can actually turn the key to start, hold it there for a couple seconds and it will continue turning the starter even if you release the key.
When this system starts to fail it causes the issue you have. One of the first things I try is to disconnect the battery terminals. Hold them together for about 20 seconds and then reconnect. This resets the various items in the computers and sometimes will fix a computer module that got "confused"
Beyond that is to re-flash the control module or replace it and flash the new one.
I have seen the ignition switch be the issue once with this problem so you could unplug the harness to it and see if the problem persists.
This all supposes that nobody installed a non factory remote starter on the car, if one is there then it could be the issue as well.
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Monday, June 26th, 2017 AT 3:48 PM