FRONT BREAK IN HARLEY WITH ABS

Do you mean the brake it self, or the abs? I f it is the brake it will certainly either the caliber or the master cylinder. Loosen the bleeder valve on the caliber and give a little pull on the brake lever, check for fluid at the bleedervalve no fluid =bad master cylinder, fluid means bad caliber. this is assuming you have checked the fluid level. Make sure to check on the master cylinder for proper type of brake fluid, my HD uses dot 5. If you are talking about the abs, the most common issue is the wheel sensor connector being loose or bad, all check the wiring to make sure it is clean and tight.