Hey there, I’m getting a battery light warning when my truck gets over 3k rpms. I just replaced the alternator and after going to autozone when it first went on. They told me it was showing “battery disconnected from the light” and when testing my battery it came back good. I have looked at all connected they are all tight and wiring is in good condition. I have read elsewhere maybe serpentine belt? Thanks in advance

 

Clean the terminals, see if there is voltage drop under load. Check your coils and their wiring harness. Serpentine belt is reasonable to replace but check the tensioner first. Make sure the battery is the proper amperage.

 

took it today and they think it’s the ECM, wondering how hard it is to install a preprogrammed unit from autozone

 

Search up threads on crack ecms here. They'll give you a better answer and you can compare it