Hey Riggo... The AHM module is an extension of the LCM module, it provides the lighting solutions for the trailer lights (non-LED), and when the trailer lights are connected, the AHM will disable the rear PDC if so equipped, will disable the manual operation of the 4-corner ride height control, if so equipped and will disable the rear fog lights if so equipped, or if wired properly through the LCM and not via the trailer module (see the rear fog threads on this forum). The AHM will not provide the brake control, but you already know that...
If your trailer has LED lights, you can get yourself a 7-pin to 4-pin converter (the US plug is 4-pin), and solder in three resistors that will act as additional load for the AHM to make it think that there is an incandescent light bulb - also is helpful to have the 7-pin-to4-pin adapter with resistors if you hook up a basket or bicycle carrier, the adapter will cut off the annoying rear PDC...
you can see the adapter in my thread referenced in my signature...
Congratulations on the install!!