There is no serviceable flasher. The bulb flash time (80 per minute) is controlled by the BCM. When it detects a bulb out (or a low resistance LED) it flashes 160 times a minute. The sound you hear is created by the cluster to mimic the sound of a conventional flasher. If you search the forum, or someone may chime in, there are resistors you can get to add to the turn signal circuits to slow down the flashing.
2011 FX2 SCrew Sterling Grey 5.0 5Star tuned, Roush CAI w/ factory tube, Turn signal mirrors w/ running lights, Center console lights, Puddle lamps, Bak-flip tonneau, Add-on factory camera, Roush coil covers, Mustang engine cover, Power tailgate lock,
Sound Ordnance B8-PT sub under passenger seat, Infinity Kappas in the doors, Bilinvic Retrofits headlights