I have a 2001 B3000 that had bad head and cylinder so I decided to just to a full engine swap. I found a 2005 Ranger engine and transmission combo that came with the wiring harness also that only had 110K miles on them. I am using the original computer form the 2001. I finally got the engine in today and hooked everything up including all the electrical, but have not put the exhaust, drive shaft or radiator on. I wanted to make sure the truck would start before I went any further. When I try to crank the truck nothing happens at all. My first thought was that the transmission was not in park or neutral. I climbed under the truck and moved it through all possible positions and got the same result.

My goal was to use the 05 wiring harness because it was in better condition than the one from the 2001. Everything seemed to plug in ok except there is one connecter that is near the rear O2 sensor and I have no idea where it goes. Not sure if it is something from the 05 that was not on the 01. I have attached a picture of the connector, if you know what it is and where it goes please let me know. I am not sure if this is the reason that the truck will not crank at all.

The only real other difference is the intake is not cast like the 2001. I may have to switch the intake out so the throttle cables can be connected correctly.

Here are a few questions that I have.
Is the 2001 and 2005 wiring harness the same or can this be the reason for my issues?
Any ideas on why the truck will not crank at all?
Where does the connector in the picture connect to? We left the harness on the engine and trans and pulled it out all together, so I believe it had to hook so something on the truck.

Any help would be greatly appreciated. I am trying to get this truck running for my son.