Is there anyway to check the codes of a 2003 Duramax Like the way we can with our Cummings? My brother is having problems, surging, it feels like it's defueling between 2500-3000 rpm when you accelerate heavy, at the same time it will down shift but when it reaches 2500-3000 (as above) it will not up shift... My first thought was maybe the fuel filter is dirty, we will change that first. Can anyone recommend a site for him to join for Duramax?
Thanks,
Chas.
Thanks,
Chas.