Can someone help me diagnose this problem. I did a 4l80e swap on a friends truck and when he went to get it tuned it wouldn't take first gear.
I did have to replace the internal wire harness because the one on there was broken. Is there a difference in year models with these harnesses? Could that still be the issue?

 

Wouldn't take first gear? You mean it wouldn't start in first, so its stuck in 2nd? What method did you use to convert to 80e?

 

Yea sounds like a wiring or tune issue.

check the fuses under the hood?

i think theres a 10 or 15 amp fuse that runs the trans.

 

As stated, what year truck, what method was used wiring wise to convert and is the tune segment swapped or was the relay method used? You said you changed a wire harness, you mean the internal trans harness? Wasn't it new? There are some differences between the internal harnesses depending on year, I know the EPC solenoid had some changes as well as a couple other things just dont recall exactly what off the top of my head.

 

Ok truck is a 2000 and the trans was to be from 97 and down I believe. I replaced the internal wire harness because when I had the trans swap done went to fill it with oil it was leaking through the plugin. I have a couple pics to show on that. I used a Nelson conversion harness to to the swap and the tuner did a segment swap on it to. It just won't start off in first gear. Maybe the tuner will chime in as well on what it's doing.

 

Is it throwing any DTC's?

 

Is first the only gear it won't go into? Manual first?

 

it takes off in 2nd and if u do 1st manuely it doesnt do anything

 

Are you sure the trans is actually going into 1st and it the shift cable is adjusted correctly.

 

it doesnt go into 1st wat i ment was when u do it manually it doesnt get 1st either it just stays in 2nd