New to this forum. I'm sure the 03 battery drain has been discussed before but I couldn't rewlly find the answer I'm looking for. I have an 03 z71 tahoe. A few months ago it started killing batterys overnight. This is intermittent. Sometimes it does somtimes it doesn't. I have replaced 2 battery now. I have recently fixed the engine block ground, put in a new BCM. the battery is charged by the alternator just fine. Everything appears to shut off after vehicle is turned off and door is shut. I have tried to do a parasitic drain test and all I see is 12-14 mili amps. I'm not sure how to diganose this issue.