You will have to identify the resistor value and how they are wired into the system. The diagram on the inside door panel should help.
You will have to add a similar resistor to the new zone (4)
You will have to add zone 4 to the enabled list (wrong term but descriptive).
You will need the programmers guide (google “Programming Guide, 772.pdf”)
You will need the users guide (google “User Guide, 786.pdf”)
Reprogramming and adding Zone 4 is not difficult but is tedious (using the keypad buttons). When I did mine I thought I could just zip in and program it quickly. Did not work out for me. I had to read through the programming manual several times to get a “feel” for how the commands are structured. In the end I successfully completed my complete system from scratch.
Good luck.
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