6.0 ls1 swap wont start

[4x4k20]

i got my 6.0 with 4l80e swaped into my 77 k3500 crewcab it wont start at all i have heard that it could be the ecm needs reflashing because of the security system it was in a 2006 gmc 2500hd i have heard many things from different folks can someone tell me for sure what needs to be done to get my truck to start thanks

 

[sweetk30]

first is yes need security turned off the vats system .

then go threw the wiring and recheck stuff.

i read up here on mine . ( not done with resto yet ) havent tryed mine yet. http://www.lt1swap.com/2000harness.htm

 

[TSewell]

Turn off VATS. Its a pain in the ass to find it, and turn it off, but a good tuner can get it done. If you lived closer i would help you. While its at the tuner have him/her get it started, as its going to need to be tuned anyways, so you might as well get it done a the same time.

 

[texas4x4rebel]

if it starts then dies right away it the vats also if the pcm has never been flashed its defiantly the vats.