Reman Ecm problems, misfiring, trying to plug the old one back in

Good evening,

I currently received my re-man ecm because the stock one started leaking fuel. Well took old one out put re-man in and started up truck and truck ran like crap. Sounds like it was misfiring and check engine light was one. Took re-man out put stock one back in. And now I can't get wiring harness to plug back in. All they want to do is fall out. I zipped tired them in and went to start truck and truck cranks but won't start. What happend truck ran fine before I don't know what to do

 

Just throwing this out there, are you tightening the allen head bolt in the center of the harness plug that holds it in?

 

There is no allen bolt. I'll take picture of harness tomorrow but yea deffinatly no Allen bolt present on the harness clip ends that go into ecm

 

You do not have the correct replacement ECM. One has threaded studs for the connectors and the other does not.

 

That's why I asked, I saw the studs on the new one.

 

That was my thought as well. New ECM also has male pins, looks like female on the original. Unless there's parts missing from the pictures?

 

Definitely need pics of the harness plugs, something wrong here.

 

Just woke up. Heading to truck now to go take pictures of harness

 

Part of the harness plug is missing. Those female pins should not be exposed like that.