Scangauge 2 broke my OBDII and is causing problems

So I figured out what the issue was and I feel like a complete idiot...
After getting the replacement OBDII female plug in the mail, I cut off the old connector and cut the wires back to a point where they weren't melted together. Although after the new one was all wired in, I was still having the same problem!
I sat there looking through forum posts online and probing all sorts of wires with my multimeter trying to find something wrong that would cause the problem.
I found a forum posts where a guy said to check every ground in the truck (which there are many of) to make sure they are all secure. I was pretty confident that all grounds were all good, but I figured I might as well check again. First one I checked was the ground on the lower intake manifold in the engine bay, and sure enough it was not tightened all the way down! After securing it, the problem was solved!! So relieved to have fixed that problem!!

Thanks to everyone who posted with suggestions and trying to help me get my truck up and running again!!!

 

That cant be the cause of the melted plug tho..? I mean, there has to be a decent amount of juice running through there to do that.. Did you find an answer on that front?

 

My best guess is that the connections were already slightly oxidized and corroded which led to a higher resistance connection therefore causing a build up of heat in the connection.

 

Was that ground on the right or left side of the engine? If left side, yep that was probably what started all this.

Yessir. And it chose the path of least resistance. Did that terminial on the intake look like it had been arcing at all?

 

It wasn't stupid loose, just enough to barely not make contact with the intake manifold. No arcing from what I could tell.
The ground I am talking about is the one on the lower intake manifold of my 3rz on the driver side closer to the front of the engine bay (toward the radiator)

 

Ah okay. I just have a 2003 3RZ EWD, and the ground is on the RH side for that year. Not familiar with the before 2001 trucks... But on the 03 3RZ, one ground pin on the OBD connector attaches to the inner pass. side fender in the cab and the other ground pin attaches to the intake. I think you nailed it. Thanks for updating a resolution!

 

Shit happens, least you fixed 2 problems.