I think there are two issues. My 21 Sierra was not starting on the first attempt but started on the second attempt at least once per week. I had the ECM update applied and that issue hasn't happened since. There is another issue that prevents the truck from starting for roughly 30 minutes. That has beppened five times since I bought the truck new. It will show a low battery voltage warning after not starting on the second or third attempt. Is there any known fix for the second issue? My local dealer isn't very good and won't do anything unless I can give them a TSB number.
