I have a 2008 Tahoe with 5.3 and 4l60 transmission and I have a 2010 Tahoe with 5.3 and 6l80 transmission. I installed the 2010 engine and transmission with the wire harness. I changed the PCM and cluster. It cranks but the fuel pump is not turning on. There are some connectors I can't find plugins for.
Do I have to change all wiring and switch out more parts for it to work?
they made changes in 2010 so short answer is probably yes.
the problem you may be experiencing is the fuel pump control module, the module has to be programmed to the vin so.... that could be the issue and/or if it is wired different
if they look like the harnmess is the same you could try swapping in the module off of the 08 onto the 10, but you may still need to have it learned to the vin.
it may be worth noting that dorman sells a fuel pump module that does not require programming, so that "might" be a optional as well
let's see if anyone else has some idea's
@iamdub @randeez @swathdiver @Fless