hi my brothers truck pcm can be read and tuned but not scanned...

i have 2 other trucks that scan no problem

with the v2 attached to the odb 2 and the v2 connected to my laptop i enter the vin in the scan tool select the engine size also....
so far so good! the pids have no x through them and appear to be supported!

now i click connect, yellow button in the scan tool

only 3 pids are valid ... the rest have a red x and there is no data from any selected or valid pids

truck is an 03 sierra 1500 5.3 lm7
please help