What was found
(CAN) AFTER GEAR UP SELECTION AT APPROX 10000FT THE RT RED GEAR UNSAFE LIGHT ILLUMINATED. . CREW CARRIED OUT A GEAR EXTENSION AND RETRACTION AND THE LIGHT REMAINED ON FOR THE COMPLETE CYCLE. 1) TROUBLESHOOTING C/O. LDG SELECTOR HANDLE REMOVED AND TESTED. TESTED OK. PSEU REMOVED. LIGHT REMAINED ON. WIRING FROM PSEU TO LDG SELECTOR RUNG OUT AND MEGGARED TO GROUND. NFF. SUSPECT ADU AT FAULT. ADU REPLACED. NO FIX. LIGHT REMAINS ON WITH ADU CONNECTORS REMOVED. ORIGINAL ADU REINSTALLED. LDG SELECTOR HANDLE TESTED WITH KNOWN GOOD HANDLE. LDG GEAR SELECTOR HANDLE FOUND AT FAULT. ALL ORIGINAL EQUIPMENT REINSTALLED ON A/C. 2) CARRY OUT OPERATIONAL TESTS OF THE FOLLOWING SYSTEMS DUE TO REMOVAL/REINSTALLATION OF EQUIPMENT. PSEU ADU EMU 3) LANDING GEAR CONTROL SELECTOR HANDLE REPLACED AND TESTED SERVICEABLE IAW AMM 32-31-01. R/H GEAR UNSAFE LIGHT REMAINS OUT WITH GEAR IN THE SELECTED POSITION. PSEU TESTED SERVICEABLE IAW AMM 32-61-01, ADU TESTED SERVICEABLE IAW AMM 31-51-26 AND EMU TESTED SERVICEABLE IAW AMM 77-31-01 AND 77-31-00. 4) GEAR SWINGS CARRIED OUT. LEFT GEAR IN THE UP POSITION FOR 30 MINUTES TO ENSURE NO FAILURE LIGHT ILLUMINATED. GEAR SWINGS COMPLETED SERVICEABLE IAW 32-31-00.