I put an 09 Duramax drivetrain in a 2008 Suburban 2500 and I've tried everything to get this 4x4 to work!! I swapped the following parts with a truck that is working, front actuator, encoder motor, transfer case module, speed sensor above the encoder motor, fuses and I have checked voltages as well. I even put the duramax body control module in as well just to see!! So there is no indicator lights on the switch to tell you if your in 2wd or 4wd. At start up all the lights light up for a second then disappear. I tried the reset with the switch but nothing happened. So the Tech 2 says C0321 Transfer Case Module Lock Circuit Open.