My howler pulsates

[RBRONKEMA GHTFD]

Good afternoon gents. I just completed a install for my department, we got all new whelen equipment. We're running a SLSA6 whelen siren and a 100 watt howler. I should mention that we are only running 1 100 watt siren speaker also. We're switching the howler through the one of the sirens push buttons. It is programmed as a momentary switch, while it works great for about 2-3 seconds it will then start pulsating. I have double and triple checked my wiring and for the life of me cannot figure out why it pulsates. Does anyone have any insight as to why it is pulsating.

 

[RBRONKEMA GHTFD]

Anyone, Anyone at all?

 

[MtnMan]

Back-probe the +12V and ground terminals at the Howler amp connector and make sure it's getting solid power while operating. If that's not the problem, it's probably going to be a factory repair.