I learned the solution was to program the M1225 for "COR Active Low."
This was easier said than done. Nowhere in the Motorola software did I see an obvious place to program COR Active Low.
A little trial and error revealed the solution.
In the Motorola software, go to External Accessories
Program PIN 8 as "CSQ Detect", "Output" and "Low", as shown in the image below.
|Program PIN 8 like this to achieve COR Active Low|