What are my options here? I can't make this transmission work? Or do I absolutely have to swap it out?
You have one, maybe two options:
1). swap it for the correct year transmission for that vehicle. That's it.
The following changed in 2009:
- MLPS and Pressure switch manifold replaced with Internal Mode Switch
- 3-2 control solenoid deleted
Your computer's command and control are looking for the psm and the 3-2 control solenoid and are not seeing them. The IMS must be sending a correct P/N signal to the PCM otherwise you wouldnt even be able to start the truck.
Call the GM Dealership-Parts and see if they can assist you with transmissions that have a compatable set of 3-character ID codes, as shown on the ID tag, for your truck. This way you know exactly what to look for...
That's your best bet for now.
2). If you're up for it, remove the valve body, separator plate and anything else bolted to the underside of the case and take a VERY GOOD picture of the worm tracks. If they themselves are the same as all other years, then it may be possible to swap in a valve body, spacer plate, harness and full electrical package for a 2007/2008 model year unit.
But id call the dealer first.