Diagnostic mode

A computer system's diagnostic mode is used to ascertain whether or not there are problems or inconsistencies in a starship's main systems, including the transporters.

When Miles O'Brien, Data and Deanna Troi, taken over by Ux-Mal criminals, wanted to make sure that nobody could use the transporter to beam them back to Mab-Bu VI, O'Brien took the entire transporter array off line and placed the transporter in a diagnostic mode which would take hours to complete its cycle. (TNG: "Power Play")

Types of diagnostic modes

Level 1 diagnostic

A Level 1 diagnostic is a troubleshooting/test series that requires taking the associated system off-line.

In 2369 Chief Miles O'Brien ran a level 1 diagnostic of the runabout Ganges' systems, including the central power linkages. (DS9: "Q-Less")

The same year he told Julian Bashir that he was thinking of running a level 1 diagnostic of the phase coil generator when he was back aboard the station. (DS9: "The Storyteller")

O'Brien ordered Neela to run a level 1 diagnostic of the runabout's computer interface in 2369 after they've discovered that Ensign Aquino was murdered there. (DS9: "In the Hands of the Prophets")

One of the peculiarities that allowed William Riker to discover that what he originally thought was the future was actually a fabricated reality was noticing that La Forge's level 1 diagnostic had lasted for more than 30 hours, displaying an uncharacteristic level of incompetence. (TNG: "Future Imperfect")

• TNG:
  • "Evolution"
  • "Remember Me"
  • "Hollow Pursuits"
  • "Data's Day"
  • "The Mind's Eye"
  • "The Next Phase"
  • "The Quality of Life"
• DS9:
  • "The Forsaken"
  • "Past Tense, Part I"

Level 2 diagnostic

• TNG:
  • "Remember Me"
  • "Aquiel"

Level 3 diagnostic

Lieutenant Farrell requested permission from Geordi La Forge to run a level 3 diagnostic on the USS Enterprise-D's port plasma relays, as she had noticed one of the generators was fluctuating. (Star Trek Generations)

In 2369 Commander Benjamin Sisko ordered a quick level 3 diagnostic of the graviton generator because of the residual charge readings. (DS9: "Dax")

The same year Chief Miles O'Brien ran a level 3 sensor sweep through the promenade to detect anomoulos readings after he found the program ANA. (DS9: "In the Hands of the Prophets")

• TNG:
  • "The Nth Degree"
  • "Schisms"
  • "Cause and Effect"
  • "Aquiel"
  • "The Chase"
  • "Phantasms"
• DS9:
  • "The Assignment"
  • "Doctor Bashir, I Presume"
• VOY:
  • "Caretaker"

Level 4 diagnostic

Level 4 diagnostic

Locking a starship's transporters diagnostic mode, effectively putting it into a diagnostic cycle, will keep any inert matter in the pattern buffer. Ordinarily, inert matter can only remain in the pattern buffer for seven minutes before becoming irretrievably lost, but Montgomery Scott was able to reconfigure a transporter, locking the pattern into a level 4 diagnostic cycle to keep his pattern in the pattern buffer for 75 years. His pattern was retrieved with minimal degradation. However, another occupant was not so lucky and was lost. (TNG: "Relics")

• TNG:
  • "Cost of Living"
  • "Genesis"
• VOY:
  • "One"
  • "The Haunting of Deck Twelve"

Level 5 diagnostic

• TNG: "The Mind's Eye"
• VOY:
  • "Drive"
  • "Repression"

Security diagnostic

• DS9: "Behind the Lines"

Other

• In 2369, the Bajoran engineer Neela ran a diagnostic of the modifications she did before. (DS9: "Duet")
• Complete systems diagnostics. (VOY: "Parallax")
• Transtator assembly diagnostic. (VOY: "Time and Again")

Sources

• Janet's Star Trek: Voyager Site