Wash jars and lids in hot soapy water; rinse with warm water. Fill boiling-water canner half full with water; add jars and water to cover. Bring water to a boil, reduce heat and simmer. Place lids in water to cover in a small saucepan; bring water to a simmer. Place lids in water to cover in a small saucepan; bring to a simmer. Simmer until ready to use. Remove and drain jars and lids, one at a time, as needed for filling.
Combine vinegar, water, SPLENDA® Granulated Sweetener, mustard, celery seeds, turmeric, and salt in a large Dutch oven, stirring until SPLENDA® Granulated Sweetener dissolves. Add corn, onion, and bell peppers and bring to a boil; reduce heat and simmer, covered, for 15 minutes.
Pack hot vegetables immediately into prepared jars using a slotted spoon, filling to within 1/4-inch from top. Ladle liquid into jars, filling to within 1/4-inch from top. Wipe rims and threads. Cover with 2-piece lids. Screw bands tightly. Place jars on rack in canner. (Water must cover jars by 1 to 2 inches. Add boiling water, if necessary.) Cover; bring water to a gentle boil.
Process 15 minutes. Remove jars and place upright on towel to cool completely. After jars cool, check seals by pressing center of lid with finger. (If lid springs back, lid is not sealed and refrigeration is necessary.) Store in a cool, dark place for up to 1 year. Once opened, store refrigerated and use within 2 weeksServings: 32