Lost connection to ecm

[Jessiebandz]

Hey guys I’m in a bit of a tough situation. I’ve been having issues regarding my 16 Sierra 1500 Denali . To when it first started, I was driving and my trucks gauges just randomly shut down felt like my truck was driving on first so I pulled over turned off the truck and when tried to turn back on got nothing. Got it to turn on 30 min later took it to the dealer and they replaced my battery and called it a day. Ok next time comes around coming from work after I hit a speed bump. This time I didn’t pull over and tried to make it home . I made it home and after that the trucks gauges  down and they went back up after a while of driving and went back to normal .( this happened most times.) took it to the dealer said it was my battery again and replaced it . This is when my red flags start rising. I forgot to mention recently the times it’s done this I got a check engine and codes that read failed to connect to ecm/pcm ,cylinder misfire . Long story short this has been happening for a while but now more recent and tend to happen when I hit a speed bumpS. I went as far as replacing my ground ( battery to frame), checked the ground inside the cabin near the steering wheel , and even checked if I was getting power to ecm and grounds . It’s becoming so frustrating because at times it will be perfectly fine and other times just won’t even start. Just unreliable. Any help would be REALLY appreciated. Already got sent back from the dealer and they said they didn’t know what it could be.

[steelerdude15]

Did you check the ground behind the passenger front splash shield? This is a popular one people clean/retighten and helps with their electrical issues.