As an example, a 23 code would be indicated by FLASH, FLASH, PAUSE, FLASH, FLASH, FLASH.  Multiple codes may be displayed, and the sequence always ends with 55.  Green codes will light the CHECK ENGINE lamp when the engine is running.

CODE      MEANS
  11           No crank signal detected during cranking
  12           Battery was disconnected within the last 50 key-on cycles (Resets after 50)
  15           No vehicle speed/distance signal while driving
  23           Intake manifold air temp sensor voltage  too high or too low
  24           Throttle position sensor voltage too high or too low (automatic only)
  33           An open or shorted condition detected in the AC clutch relay circuit
  34           Open or short in the Speed control solenoid circuits  or
                 Speed control switch voltage too high or too low
  37           Open or short in the Torque converter clutch solenoid CKT circuit  or
                 Voltage high or low  at transmission Temperature sensor
  41           An open or shorted condition detected in the alternator field control circuit
  42           An open or shorted condition detected in the Auto Shutdown Relay circuit
  44           An open or shorted condition detected in the engine coolant temp sensor circuit  or
                 A problem exists in the PCM battery temperature / voltage circuit
  45           An open or shorted condition detected in the overdrive solenoid circuit
  46           Battery charging system voltage too high
  47           Battery charging system voltage too low
  53           Internal PCM circuitry or communication failure
  55           End of sequence.  Last code sent to indicate the end of the codes.
  62           SPI miles not being updated as vehicle travels
  63           Unsuccessful attempt to write to EEPROM by the PCM