What was found
ON FINAL GOT NO GEAR DOWN & LOCKED INDICATIONS ON HANDLE OR EAD SYNOPTIC, LIGHTS ALL RED, WENT AROUND, RAN QRH GEAR LIGHTS ALL GREEN AFTER QRH. SUSPECT SWITCH INDICATOR AS MULTIPLE WRITE UPS. FAILED OPERATIONS CHECK & ORIGINAL UNIT REINSTALLED. TROUBLE SHOT PSEU THRU MCDU ALL SENSOR READ OUT & TARGETS READS OK. PERFORMED RTS ON PSEU ALL TEST PASSED, ATTEMPTED TO REPLACE PSE PRECAUTIONARY IAW TO 31-71-01-2 NEW UNIT FAILED OPS TEST WITH INTERNAL FAULT CODE 317046 ORIGINAL UNIT REINSTALLED & OPERATIONS CHECKED IAW MM 31-71-01-2. NO CURRENT FAULTS, TEST PASSED, ACFT OK TO CONTINUE SERVICE.