What was found
NR 2 ENGINE BLEED GIVES NO DUCT PRESSURE WITH ISOLATION VALVE IN AUTO OR CLOSED. RETURNED TO DEPARTURE AIRPORT, EXECUTED LOW SINK RATE LANDING. REMOVED AND REPLACED NR 2 ENGINE BLEED AIR REGULATOR IAW AMM 36-11-03-4. ENGINE NR 2 BLEED SYSTEM OPS CHECKS NORMAL. IAW MAINTENANCE CONTROL HNL PERFORM PRECAUTIONARY CHANGE OF WIRE HARNESS MW0311, REF: 737NG FTD-36-00001. REMOVED AND REPLACED MW0311 WIRE HARNESS IAW AMM 73-21-06-4. FADEC SYSTEM TEST PERFORMED IAW AMM 73-21-00-5. SYSTEM PASSED TEST. AIRCRAFT RETURNED TO SERVICE.