Great photo IMHO <| sep |> The core problem was that the telemetry wasn ' t sending back data properly , and the ApolloSaturn V needed to be flown by not just the astronauts but by the control room as well . SCE stands for Signal Conditioning Equipment which reads various signals within the spacecraft and translates it into digital form to send through the telemetry connection . When the power went offline that equipment lost its voltage references and couldn ' t read data properly . Switching SCE to AUX switched to an internal reference that allowed the data to be read and digitized successfully , restoring the telemetry . After which the astronauts and flight engineers on the ground could work their way through the issues facing them , bring the spacecraft back online and continue with the mission .