What was found
TCAS EICAS AND -TCAS FAI L- ON ND. TRIED L/R CYCL ED. NO HELP. C ALLED TOMC MMSG 34-28801 CAPTURED IN AHM BUT NOT AUTOMATICALLY CORRELATED TO TCAS FAILURE ADVISORY/STATUS. IN FIM THIS MMSG DOES CORRELATE TO OBSERVED TCAS FAILURE. OTHER ADIRU FAULTS CAPTURED IN AHM. SUGGEST REPLACEMENT OF ADIRU ALONG WITH OTHER MAINTENANCE AS DEEMED NECESSARY BY TROUBLESHOOTING. IADLM WEBBER PERF. TCAS SYSTEM BITE REF. AMM 34-45-01. UNABLE TO DUPLICATE FAULT, TCAS SYSTEM OPS CHECKED GOOD. AS PRECAUTIONARY, REMOVED AND REPLACED TCAS COMPUTER REF. AMM 34-45-01. OPS CHECK GOOD.