Place turkey breast in the slow cooker. Season with salt and pepper and pour chicken broth into the bottom of the slow cooker.
Cook on low for about 8 hours, or until a meat thermometer reaches 170 degrees F in the thickest part. Remove from slow cooker and let rest for 5-10 minutes before slicing. Place back in the slow cooker and set to keep warm.
In a small pot, combine preserves, vinegar, garlic and brown sugar. Bring to a simmer over medium high heat, and reduce to medium, whisking often.
Simmer for 15-20 minutes until reduced and thickened slightly (it won't become super thick, but there will be a noticeable difference -- it will continue to thicken as it cools). Pour over turkey slices in slow cooker and serve.