What was found
MAINT MSG 77-20861 {BOTTOM LEFT EGT SIGNAL (T495S3) IS OUT OF RANGE - LONG TIME FAULT (450 FLT HRS) DEFERRAL PER T/C 78273000. GROUNDED - YES. FOUND S4 EGT READING TO HAVE DASHES. ACCOMPLISHED T49.5 AND EGT SYSTEM INSPECTION REF B737-900 AMM 77-21-01-200-801-F00. CONTINUITY CHECKS ARE WITHIN LIMITS FOR ALL HARNESSES AND PROBES. ACCOMPLISHED EGT CLEANING REF AMM 77-21-00-140-801. ACCOMPLISHED EEC TEST REF AMM 73-21-00-700-804-F00. NO FAULTS FOUND. GROUND VERIFICATION SUCCESSFUL.