Need help with wiring

[Sunday1234]

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?

 

[Doubeleive]

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

 

[iamdub]

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?

Pretty much what Wes said. In addition to the FSCM, the BCM will need to be reprogrammed or swapped. I'd say reprogrammed, but only if all the wiring is all the same (both Tahoes equipped/optioned the same, etc.) Probably easier at this point to swap the rest of the wiring, etc. from the 2010. My question is if you have inspections, how are you gonna pass when they plug in and it shows a 2010 but your VIN shows a 2008? Maybe you can have the correct VIN flashed onto the PCM and into all the modules without affecting their function?

 

[Sunday1234]

Alright I'll look into it. I forgot to mention that there is a couple plugins I can't find.

 

[Sunday1234]

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?

I got the vehicle started going. I had to change steering wheel, fuse boxes, PCM, cluster. I set up a appointment to get the bcm flashed. The down side I had to change out the air ride and replace front struts, coil springs, and shocks.