I have a 2003 Saturn Vue that will start and run then die after 2 seconds or so. I thought we needed to reset the security, but the Security light never comes on. I get both the service and the service with a wrench. I put it on a computer and we get the U2107 code. Can a weak battery be the culprit? I cleared the code and it started then as soon as I turn it off, the code is back and it starts then dies. I'm told that it needs a BCM, but the code indicates that the BCM cannot communicate with the ECM. Help?