Lights on warning buzzer kit

Yesterdays buzzer would change in volume and tone. Sort of like a horn blowing on a dead battery.
This little 90 db PIEZO buzzer with built in driver requires only 3 V dc and draws 5mAmps. I dont believe the dimmer would effect it.
Since I have that dimmer bypassed in my car , I cant run out and test it. I'll take your concern to the workbench first thing tomarrow morn. Thanks