I agree sounds to me like a bad ground somewhere in the system, I would start with the battery ground cable and give it a good thorough inspection and if nothing was discovered I would move to the ground strap under the car that goes from the frame to the transmission bellhousing. I would also take the cover off of the RCM box next to the battery and move the wires around that go to the plugs on the RCM and the BCM and the ECM sometimes the plugs lose continuity and just moving the connectors around can re-establish connection, I know this can happen because I had to do that to my BCM module and all was well afterwards.. good luck and I hope this helps.