Your better off taking it to the dealer , after replacing it needs to be programmed or it will not run . Information from the old has to be up loaded to GM Tech 2 scan tool to load on new one ! Then you would need to pay for a subscription to GM'S service programming system to get software to program new ECM .
Program the ECM. Refer to Service Programming System (SPS) in Programming. If you encounter an ECM programming error, with a display message of "Starting Disabled, Remove Key" on the driver information center, with a diagnostic test code (DTC) of P1631, perform the "10-Minute Relearn Procedure" found in Programming Theft Deterrent System Components. Refer to Programming Theft Deterrent System Components . Additional information can be found in service bulletin number 05524 A. Turn OFF the ignition for at least 5 seconds after the programming event is complete. Perform the idle learn procedure. Refer to Idle Learn . Use the scan tool to clear all DTCs.
Of if you a few grand you could buy a J2534 programming tool an
J2534 Reprogramming Tool