Left rear door ajar message

[Gajumper]

Hello, first post here. I have an 03 LT that has an intermittent 'left rear door ajar' message accompanied with the interior lights coming on. I have read quite a few posts concerning this issue and have tried to run down the problem. So far I have checked the resistance on the switches at the latch and BCM. I cleaned the switches and lubed the latch. Everything seems to be pointing at the BCM being the culprit. My question(finally) is does a new BCM need to be programmed? or is it just the used ones? Thanks