Diagnostic mode

A computer system's diagnostic mode was used to ascertain whether or not there were 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 was a troubleshooting/test series that required taking the associated system off-line.

In 2369, Chief Miles O'Brien ran a level 1 diagnostic of the runabout USS 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 generators when he was back aboard space station Deep Space 9. (DS9: "The Storyteller")

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

One of several peculiarities that allowed William T. Riker to discover that his "future" was actually a fabricated reality was noticing that a level 1 diagnostic Geordi La Forge had apparently been running had lasted for more than thirty hours. This displayed an uncharacteristic level of incompetence, as the same diagnostic would have never taken the real La Forge more than four hours to complete. (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:
  • "Tin Man"
  • "Remember Me"
  • "A Fistful of Datas"
  • "Aquiel"

Level 3 diagnostic

A level 3 diagnostic listed on a display

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 residual charge readings. (DS9: "Dax")

The same year, Chief Miles O'Brien ran a level 3 sensor sweep through the promenade to detect anomalous 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, would keep any inert matter in the pattern buffer. Ordinarily, inert matter could only remain in the pattern buffer for seven minutes before becoming irretrievably lost, but Montgomery Scott was able to reconfigure a transporter aboard the USS Jenolan, locking the pattern into a level 4 diagnostic cycle to keep his pattern in the pattern buffer for seventy-five years. His pattern was retrieved with minimal degradation. However, another occupant, Ensign Matt Franklin, was not so lucky, his pattern having degraded beyond all hope of retrieval. (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 2151, Trip Tucker ran diagnostics in engineering and found a power surge in the transceiver array. (ENT: "Breaking the Ice")
• In 2153, Trip Tucker ordered Haynem to perform a diagnostic of Shuttlepod 2, as the impulse assembly had taken some damage. (ENT: "Impulse")
• In 2369, Bajoran engineer Neela ran a diagnostic of modifications she had made before. (DS9: "Duet")
• Complete systems diagnostics. (VOY: "Parallax")
• Transtator assembly diagnostic. (VOY: "Time and Again")

Background information

From the entry "diagnostic" in the Star Trek Encyclopedia (4th ed., vol. 1, p. 208), "Engineering analysis programs used aboard Federation starships, intended to permit automated determination of system performance and identification of any malfunctions. Most key systems had a number of such programs available, ranging from level-5 diagnostics (the fastest, most automated) to level-1 diagnostics (the most thorough, but the slowest, requiring the most manual labor)."

Sources

• Janet's Star Trek: Voyager Site^(X)