As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THRUST MODE DISPLAY SHOWS ALL DASHES (---.-) NO N1 DATA IN FMC. GROUNDED - YES. VERIFIED DISCREPANCY. C/W AIRCRAFT POWER DOWN FOR TROUBLE SHOOTING PROCEDURE. AFTER POWER UP OF ALL AIRCRAFT SYSTEMS PILOTS REPORT THRUST MODE IS NOW DISPLAYING ALL NECESSARY DATA. REF B737-900 AMM 20-60-99.