Ok guys I'm new here but I sure hope you can help us out. I'm working on my wife's car its a 2007 Pontiac gp gxp. I just installed a new tep transmission after setting for 2 years. All went well except battery kept going dead over night (new battery) so checked alt is good then replaced starter as soon as I hooked up the battery the engine tried to turn over (key out of ignition) so found car was throwing code for ignition switch or ecm bad (can't remember what number code) so I installed new ignition switch same problem after so I bought a used ecm off eBay programmed to my vin and then theft system prevented starting even though car would randomly try to start itself. Next I took it to gm dealer after I couldn't get the key relearn to work. They said bcm was bad along with key tumbler assembly they replaced them 800 later I still have original issue. They said fuse panel is bad. I brought it back home removed panel and dissasembled it. I found a small amount of corrosion but nothing alarming I cleaned it and reinstalled. I then had code p1682 after clearing it would come back on next key cycle then I cleared again and it stayed off I drove car about 5 miles no problems came home turned car off now if I turn key to run position and back off check engine light turns on even without key in ignition if I start car then light goes out. I'm baffled any help greatly appreciated thanks fellas