JoshRushing

I had a Saturn L300 recently that had multiple issues with the BCM (lighting, wipers, shift lock, etc.) in addition it also had an intermittent "No Start" issue. It came in as a "No Start", I began troubleshooting (blah,blah,blah) and pulled the BCM to check for bad connections and possible bad solder joints. I re-flowed the solder joints and luckily corrected the "No Start", however the other issues still existed. Don't ask why, but at one point I reconnected the BCM, started the vehicle, then disconnected the BCM. After the initial reconnect and start up, the vehicle would continue to start with the BCM disconnected. It would restart without the BCM until I disconnected power to the ECM. I even used the TECH 2 to put all modules to sleep and it would still restart without the BCM. It would ONLY reset and look for security data after disconnecting power directly at the ECM or unhooking the battery. I installed a new BCM, flashed it and all problems went away. With the new BCM installed it will not run with the BCM disconnected.
After mentioning corrupt files, I am wondering if the bad BCM somehow sent corrupted security data to the ECM, that for whatever reason prevented the ECM from looking for the security data again thus allowing a restart with the BCM disconnected, until I disconnected power from the ECM and at which point it would reset and look again only to get corrupted data again.......
One other thing I found odd it that after installing the new BCM it would only allow the on board passlock relearn, it would not allow any other method to work.
 
 
 

I had a Saturn L300 recently that had multiple issues with the BCM (lighting, wipers, shift lock, etc.) in addition it also had an intermittent "No Start" issue. It came in as a "No Start", I began troubleshooting (blah,blah,blah) and pulled the BCM to check for bad connections and possible bad solder joints. I re-flowed the solder joints and luckily corrected the "No Start", however the other issues still existed. Don't ask why, but at one point I reconnected the BCM, started the vehicle, then disconnected the BCM. After the initial reconnect and start up, the vehicle would continue to start with the BCM disconnected. It would restart without the BCM until I disconnected power to the ECM. I even used the TECH 2 to put all modules to sleep and it would still restart without the BCM. It would ONLY reset and look for security data after disconnecting power directly at the ECM or unhooking the battery. I installed a new BCM, flashed it and all problems went away. With the new BCM installed it will not run with the BCM disconnected.
After mentioning corrupt files, I am wondering if the bad BCM somehow sent corrupted security data to the ECM, that for whatever reason prevented the ECM from looking for the security data again thus allowing a restart with the BCM disconnected, until I disconnected power from the ECM and at which point it would reset and look again only to get corrupted data again.......
One other thing I found odd it that after installing the new BCM it would only allow the on board passlock relearn, it would not allow any other method to work.