With all of the replacing of modules was the BCM and ECM ever re introduced (programmed)? Why was the ECM replaced? I'm still thinking the TSB, but I got no answer to my questions.

 

ECM was programmed and sent to me. May need a flash or update?

 

Yes programmed, but not sure what version was put in. ECM was giving signs of failure u.e. misc codes being thrown randomly with no justification to the codes. Battery is new and lights are all good and cruise works. I do occasionally have an issue where key will not turn back because shifter does not send signal to module to release key, Yes I have had the key switch recall done.

 

What engine? size/year.

Random codes more likely the connector/wires than the computer, they don't wear out. The key release has more to do with the battery health, nothing to do with ECM or BCM.

 

The shifter problem could be an extended service replacement, mine did that just two years ago, GM replaced the transmission control ( shifter assembly) free of charge.

A new battery doesn’t mean a good battery, it might not have been fully charged in the store, the alternator isn’t strong enough to run the computers, lights, stereo and recharge the battery.
a load test and charging test would confirm which is at fault.
12.4 volts is a dead battery, in these trucklets.

 

Did you relearn the crankshaft sensor after the ECM and engine were replaced? Or, were you told the new ECM was already done?