• Code: 7004
• Description: Toner motor Y error When the toner motor Y is driven, the toner motor Y over-current detection signal is detected continuously for 50 times (5 s) at 100 ms intervals.
• Remedy: Defective harness between toner motor Y and engine PWB (YC23), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective drive transmission system of the toner motor Y. Check if the gears rotate smoothly. If not, grease the bushings and gears. Check for broken gears and replace if any.
  Defective toner motor Y. Replace the toner motor Y.
  Defective engine PWB. Replace the engine PWB.

• Code: 7401
• Description: Developing unit K non-installing error No density detection signal is output from toner sensor K in developing unit K.
• Remedy: Faulty connection of the connector between the developing PWB K and drum relay PWB. Check the installation of the developing unit K and drum relay PWB and reinstall them if necessary.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective toner sensor K. Replace the developing unit K.
  Defective engine PWB. Replace the engine PWB.

• Code: 7402
• Description: Developing unit C non-installing error No density detection signal is output from toner sensor C in developing unit C.
• Remedy: Faulty connection of the connector between the developing PWB C and drum relay PWB. Check the installation of the developing unit C and drum relay PWB and reinstall them if necessary.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective toner sensor C. Replace the developing unit C.
  Defective engine PWB. Replace the engine PWB.

• Code: 7403
• Description: Developing unit M non-installing error No density detection signal is output from toner sensor M in developing unit M.
• Remedy: Faulty connection of the connector between the developing PWB M and drum relay PWB. Check the installation of the developing unit M and drum relay PWB and reinstall them if necessary.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective toner sensor M. Replace the developing unit M.
  Defective engine PWB. Replace the engine PWB.

• Code: 7404
• Description: Developing unit Y non-installing error No density detection signal is output from toner sensor Y in developing unit Y.
• Remedy: Faulty connection of the connector between the developing PWB Y and drum relay PWB. Check the installation of the developing unit Y and drum relay PWB and reinstall them if necessary.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Defective toner sensor Y. Replace the developing unit Y.
  Defective engine PWB. Replace the engine PWB.

• Code: 7411
• Description: Drum unit K non-installing error The EEPROM of drum PWB K does not communicate normally.
• Remedy: Faulty connection of the connector between the drum PWB K and drum relay PWB. Check the installation of the drum unit K and drum relay PWB and reinstall them if necessary.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Installation of incompatible drum unit K. Install drum unit K compatible with the specifications to the printer.
  Defective drum PWB K. Replace the drum unit Y.
  Defective engine PWB. Replace the engine PWB.

• Code: 7412
• Description: Drum unit C non-installing error The EEPROM of drum PWB C does not communicate normally. Incompatible drum unit C is installed.
• Remedy: Faulty connection of the connector between the drum PWB C and drum relay PWB. Check the installation of the drum unit C and drum relay PWB and reinstall them if necessary.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Installation of incompatible drum unit C. Install drum unit C compatible with the specifications to the printer.
  Defective drum PWB C. Replace the drum unit C.
  Defective engine PWB. Replace the engine PWB.

• Code: 7413
• Description: Drum unit M non-installing error The EEPROM of drum PWB M does not communicate normally. Incompatible drum unit M is installed.
• Remedy: Faulty connection of the connector between the drum PWB M and drum relay PWB. Check the installation of the drum unit M and drum relay PWB and reinstall them if necessary.
  Defective harness between drum relay PWB (YC1) and engine PWB (YC34), or improper connector insertion. Reinsert the connector. Also check for continuity within the connector harness. If none, remedy or replace the harness.
  Installation of incompatible drum unit M. Install drum unit M compatible with the specifications to the printer.
  Defective drum PWB M. Replace the drum unit M.
  Defective engine PWB. Replace the engine PWB.