Just got a 5.9L swapped into my 3.9L V6 99 1500. I'm continuing to use the 42RE I got rebuilt to go with it as I don't plan to hotdog the truck and eventually plan to get a built 46RE. (This is a Band-Aid fix to hold me over till I get my 408 Stroker done for it)

This is where the issues have begun.

Engine runs fine, my injectors work, some lengthened harness connectors work, etc.

Everything has gone to hell with the transmission. I'm getting a code P0753, among another one I don't remember as this was late last night, this transmission is BRAND NEW, it doesn't make sense for the solenoids to go out right way. I'm running new cooler lines and a new rad as well, didn't want to take any risks. The trans is shifting fine from 1-3 but no overdrive, and my ABS and PARK lamp are now on. I'm leaning towards it being the PCM as I grabbed a 5.9L pcm of a junkyard truck, didn't program it or nothing, I also don't think its off a 2WD truck as I wasn't thinking right at the time. I also just realized I may not have had the kickdown cable spring in the right spot, but I will deal with that later.

The truck feels VERY sluggish in first gear, almost like it's just slip slip slipping, wont shift into overdrive as said before. The shifts from 1-3 do feel VERY smooth however, maybe they're just completely slipping into gear, but they dont have the bang and clunk it did before.

Any insight into this would help, thanks,

 

ABS and such may just be a VIN mismatch. Does your trans temp light come on?

 

trans temp light doesnt come on, but it does when the plug is out, so I know it works, also your probably eright on the mismatch, Im going to order a programmed ecu first before I tear into anything.

Edit

Thought id mention to you it did blow a coolant hose (didnt overheat), and a cooler line leaks, threads on the new rad were terrible.

 

Okay, Ive formed an idea. So when I wired in the injectors for 7 and 8 had to replace the connector because it kind of just fell apart. So there's a good possibility that those pin outs I wired them wrong, so I think if I get a new ECU and a new connector for that. And redo it all and make sure double check triple check. It's all wired correctly, it should be okay. And my a b s and brake light should go out with a vin correct ecu.
As you can see the overdrive and lockup pins are infact located in this pcm connector, along with the vehicle speed pin which I know has something to do with the brakes and abs stuff.