The engine stays running when the key is out?

Tiny
RONALD DEVOLD
  • MEMBER
  • 2006 CHEVROLET IMPALA
  • 5.3L
  • 5 CYL
  • 2WD
  • AUTOMATIC
  • 232,741 MILES
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?
Saturday, May 24th, 2025 AT 11:08 AM

8 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,591 POSTS
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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Sunday, May 25th, 2025 AT 11:54 AM
Tiny
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.
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Thursday, May 29th, 2025 AT 3:37 PM
Tiny
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.
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Thursday, May 29th, 2025 AT 3:43 PM
Tiny
KEN L
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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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Friday, May 30th, 2025 AT 9:48 AM
Tiny
RONALD DEVOLD
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  • 134 POSTS
I put a new relay in and same result.
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Saturday, June 14th, 2025 AT 11:02 AM
Tiny
KEN L
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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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Sunday, June 15th, 2025 AT 10:13 AM
Tiny
RONALD DEVOLD
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No corrosion
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Tuesday, July 15th, 2025 AT 2:50 PM
Tiny
KEN L
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  • 54,591 POSTS
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.
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Tuesday, July 15th, 2025 AT 5:48 PM

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