What was found
TCAS FAIL FLAG ON NAVIGATION DISPLAY SHOWS WITH ATC TRANSPONDER SELECTOR AT TA AND SHOWS WITH SELECTOR AT TA/RA FAULT NOT PRESENT, FOLLOWING FIM 34-45 TASK 821, TCAS OPERATIONAL CHECK PASSES AND TCAS BITE PASSES. FURTHER TROUBLESHOOTING REQUIRED. PERFORMED PSEU BITE IAW FIM 34-45 TASK 821, CHECK GOOD. AWAITING EQUIPMENT TO CHECK ATC ANTENNAS IAW D 2 OF FIM 34-45 TASK 821 AFTER SPEAKING WITH TOMC AGAIN IT WAS DECIDED TO REMOVE AND REPLACE THE TCAS COMPUTER. COMPUTER REPLACED REF: AMM TASK 34-45-01 AND OPS TEST WAS GOOD.