The engine stays running when the key is out?

2006 CHEVROLET IMPALA
232,741 MILES • 5.3L • 5 CYL • 2WD • AUTOMATIC
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RONALD DEVOLD
Whenever I turn off the ignition and remove the key, the engine continues to run for about 15-20 seconds and then it will shut off. I initially thought it was the ignition, and I replaced it, but the car is still doing the same thing. Could it have something to do with the alternator?
May 24, 2025 at 11:08 AM
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STRAILER
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I don't think it is the alternator, I would try swapping out the IGN MAIN PCB relay. here is the location. Check out the images (below). Let us know how it goes.
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May 25, 2025 at 11:54 AM
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RONALD DEVOLD
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I swapped out the relay and having the same result. I also checked the alternator. its supplying the proper voltage to the battery.
May 29, 2025 at 3:37 PM
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RONALD DEVOLD
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Okay, my mistake. the diagram you posted does not relate to my car. I will have to find the IGN MAIN relay.
May 29, 2025 at 3:43 PM
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STRAILER
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The relay should be in the fuse panel under the hood on the left side of the engine compartment. This relay runs the engine control module. Check out the images (below). Please let us know what happens.
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May 30, 2025 at 9:48 AM
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RONALD DEVOLD
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I put a new relay in and same result.
Jun 14, 2025 at 11:02 AM
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STRAILER
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The ignition switch goes into the BCM so the can be the problem, but there is one more relay we need to swap out, it the pwr/trn relay which is in the same fuse panel under the hood. I would swap that out and if that does not fix it I would scan the BCM with a CAN scan to help confirm the issue. Here is how and the relay location in the images below.

https://youtu.be/u-4syLc-ifQ

Here is the BCM location as well in case you need it. You might want to unplug the BCM to check the electrical connectors for corrosion. Check out the images (below). Please let us know what happens.


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Jun 15, 2025 at 10:13 AM
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RONALD DEVOLD
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no corrosion
Jul 15, 2025 at 2:50 PM
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STRAILER
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Okay, this leaves the BCM I would do a CAN scan before replacing it. This video can show you.

https://youtu.be/u-4syLc-ifQ

Please go over this guide and get back to us.
Jul 15, 2025 at 5:48 PM
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