What was found
THE LT MLG UNSAFE LIGHT REMAINED ILLUMINATED AFTER GEAR RETRACTION LEAVING EWR. THIS WAS A REPEAT PROBLEM. CYCLING THE GEAR DID NOT HELP. THE GEAR WAS EXTENDED AND THE AIRCRAFT WAS RETURNED TO EWR WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND A RESISTIVE GROUND WIRE ON THE LEFT GEAR UPLOCK SENSOR. THE LEFT GEAR UPLOCK SENSOR AND WIRING WERE REMOVED AND REPLACED IAW MM 32-61-21, PAGE 401. OPERATIONAL CHECKS WERE GOOD.