Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Hi my name is***** will be glad to help. The common cause of this on these vehicles are a faulty ignition switch and cylinder, relay, short, or harness problem. Most likely the ignition switch, The alternator is charging keeping power to all accessories with the engine running so disconnecting the battery will not do anything. With the PCMs and electronic modules in the car and the dangers of a battery exploding from an arc while connecting the cables, you should not disconnect the battery with the engine running.
To shut it down remove the ignition relay and fuses under the fuse box under the hood. Check the harness for corrosion , damage, and shorts. If okay verify power in and out of the ignition switch for a faulty ignition switch. Let me know Click here for an FYI video.