1999 truck IOD fuse is blowing

Ok, I am helping a friend with this truck, he needs to get it passed emission testing, and the IOD fuse blows as soon as you put one in. It has the 5.2 engine, and it is a 2wd truck, regular cab. I found a wiring diagram with everything that is operated on the IOD fuse, I unplugged everything including the engine computer, and the fuse still blows. I was hoping someone may have had a similar issue before I start tearing into the wiring harness trying to find a short.


Any ideas would be appreciated, thanks!!!