Hi, glad to be of help. Since you requested me, I will give you the information requested. First, a master key as you mentioned is the original key. If you don't have the original keys, you will need to go to dealer to have them made for your vehicle. Since you replaced the theft module, the PCM will need to be programmed as well as doing the key relearn. Here is the procedure for programming the new theft module:
Programming Theft Deterrent System Components
Important: This procedure has to be performed only for vehicles equipped with
If the 10 minute learn procedure is chosen, perform the special function for
BCM "Request VTD Info. for SPS" or select Service Programming
Systems, and then refer to Programming Theft Deterrent System Components in
Procedure to setup a New Theft Deterrent Control Module
Use this procedure only if replacing the theft deterrent control module with a
GM Service Parts Operation (SPO) Replacement Part.
1. Connect the Tech 2 diagnostic scan tool to the vehicle.
2. Turn ON the ignition , with the engine OFF.
3. With the scan tool, select Setup New VTD Module in the Vehicle Theft
Deterrent, Special Functions data list.
4. Follow the scan tool on screen instructions.
* When replacing a theft deterrent control module with a GM Service Parts
Operation (SPO) Replacement Part, the module will learn keys immediately. The
existing PCM however, must learn the new fuel continue password XXXXX the theft
deterrent control module is replaced.
* When replacing a powertrain control module (PCM) with a GM Service Parts
Operation (SPO) Replacement Part, after programming, these modules will learn
the incoming fuel continue password XXXXX upon receipt of a password
message. Once a password XXXXX is received, and a password XXXXX XXXXX a
relearn procedure must be performed to change this password XXXXX A PCM which
has been previously installed in another vehicle will have learned the fuel
continue password XXXXX the other vehicles theft deterrent control module and will
require performing the 10 Minute Re-Learn Procedure to learn the fuel continue
password XXXXX the current vehicles theft deterrent control modules .
* When performing the 10 Minute Re-Learn Procedure, all previously learned keys
will be erased from the theft deterrent control module's memory.
* Additional keys may be learned immediately after the 10 Minute Re-Learn
Procedure. Refer to Adding Keys .
* When performing the 10 Minute Re-Learn Procedure, 2 master passkey III+
(PK3+) keys are required. If a gray valet key is learned first, the theft
deterrent control module will not allow additional keys to be learned.
* Tech 2 diagnostic scan tool
* Techline Terminal with current Service Programing System (SPS) software
I would recomend you go to dealer to have it programmed since you will need a tech2 scanner and Techline Terminal with current service programming system software. An independent shop may not have the tools needed to perform this operation.