Place water, soup mix, garlic and celery seed in a 6-qt. electric pressure cooker. Cut roast in half; place in cooker. Sprinkle with salt and pepper. Lock lid; close pressure-release valve. Adjust to pressure-cook on high for 50 minutes. Let pressure release naturally for 10 minutes; quick-release any remaining pressure. A thermometer inserted in pork should read at least 145°., Add cabbage and carrots to cooker. Lock lid; close pressure-release valve. Adjust pressure to pressure-cook on high for 5 minutes. Quick-release pressure., Remove roast and vegetables to a serving plate; keep warm. If desired, skim fat and thicken cooking juices for gravy. Serve with roast.