There is no difference between GM batteries or other batteries related to the alarm function. The key on the GM battery cuts all power to the controller.
The original wire harness has a red jumper wire between battery + and the "G" terminal on the controller.
If only the battery + is powered, the alarm is active.
So to have a functional alarm, a key switch should be connected in line with this jumper, breaking the jumper but keeping the rest of the controller powered will activate the alarm.
Ideally we should have a 3 position key switch with the following options:
- Run: Both batt+ and "G" terminal powered, not possible to remove key
- Alarm: Batt+ powered, "G" not powered, possible to remove key
- Off: Everything unpowered, possible to remove key
An ignition switch for a car might work, then the park position could be used for alarm mode. Most likely the switch would not handle the high currents very well, so a relay may be needed.
PS! I have not wired the alarm on my bike yet, so there is a slight chance that the above is not entirely correct
Helge