OBDII Port has no power, check engine light on

I'm trying to check my g/f's 04 silverado because the check engine light came on, but when I connect my predator to it to pull a code it doesn't power up leading me to believe the OBDII port isn't getting it either. Checked the fuses in the dash but not under the hood yet, although everything else is fine. Which fuse powers this thing? Just wanna see if I can find the problem w/o having to take it to a dealer.

Thanks in advance.

My guess would be the ECM 1 fuse. But can the truck's powertrain still operate with a dead ECM? That I don't know, does it go into default? But how can it set default values without power? These are questions that you need to know. I don't have the anwser's

Your DLC power should be supplied from the cig ltr fuse in the underhood junction box. Did you plug something into a power outlet that may have blown the fuse? Hutch

Your DLC power should be supplied from the cig ltr fuse in the underhood junction box. Did you plug something into a power outlet that may have blown the fuse? Hutch


That was it! Didn't plug anything in either of the outlets so I don't know what caused it to blow, but I replaced the fuse and pulled a P0446: Evaporative Emission Control System (small leak) checked the gas cap and it was a little loose. Guess my g/f didn't tighten it when she filled it up.

Thanks for the help!

Now I gotta try to fix the P0449 code on my Trans Am:(