Hi, I have a 98 5.2 I took it to get smogged and all passed except they said they can't read the computer in the truck. I had a code light go off and cleared it with my scanner. I guess it needs to go through a cycle for it to read again. My question is when I hook up the scanner it reads that the mil is off, should that say on and that's why its not reading the computer. Is there a setting on the scanner that will tell me that it is reading the computer and it will show up on their smog computer.

 

Check the fuses, I have seen a few vehicles that would not communicate with a scanner and the cause was just a blown cigarette lighter fuse.