How would one select a used replacement PCM for a 2002 Chevy Impala v6 to try? A friend says the current PCM has codes stored that can't be cleared even when power removed. The security light flashes occasionally, vehicle sometimes starts and shuts down (VATS?), so he would like to plug in another PCM to see if it makes a difference.

Obviously the same pcm part number and engine size is a must...just not sure how VATS plays into this year swap. If a swap corrects the problems..a VIN change would be done.

Thanks