Is there something that would cause me to lose my iat signal. I am starting to tune with "The ultimate gm efi tuning guide". I have went through the base tune steps and now have no iat on the scanner. The sensor seems to be ok, the resistance changes with the temp. I double checked the harness and it has no open circuits. Just wondering if this is something I need to look into or it is normal. Havent logged anything yet just getting started.