john yazzie

No start on 2012 gmc sierra 5.3L. put a rebuild motor in and no start now. No communication with scanner on ecm. Gm code u0100-71. Check all my grounds, clean up all my ground connections. and still no start. Anybody knows where I can check next. There's one thing I did when the motor was out was I turned the key on to check the speedometer reading, because that's what they wanted it to know, before I purchase the motor. Would I have grounded my ECM than? Thanks in advance.