• Code: 7404
• Description: Developer unit Y type mismatch error
  Absence of the developer unit Y is detected.
• Causes: Defective connector cable or poor contact in the connector. Different type of the developer unit is installed.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Developer unit Y and front PWB (YC15) Front PWB (YC2) and engine PWB (YC10)
  Different type of the developer unit is installed. Install the correct developer unit.

• Code: 7601
• Description: ID sensor 1 error
  An abnormal value is detected in the input data to ID sensor 1. Dark potential error FrontDarkP and FrontDarkS are greater than 0.80V. Light potential error FrontBrightS is smaller than FrontDarkS. FrontBrightP is smaller than FrontDarkP + 0.5V.
• Causes: Defective connector cable or poor contact in the connector. Defective engine PWB.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. ID sensor 1 and feed PWB 1 (YC10) Feed PWB 1 (YC1) and engine PWB (YC6)
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7602
• Description: ID sensor 2 error
  Dark potential error RearDarkP and RearDarkS are greater than 0.80V. Light potential error RearBrightS is smaller than RearDarkS. RearBrightP is smaller than RearDarkP + 0.5V.
• Causes: Defective connector cable or poor contact in the connector. Defective engine PWB.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. ID sensor 2 and feed PWB 1 (YC10) Feed PWB 1 (YC1) and engine PWB (YC6)
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7800
• Description: Broken outer temperature sensor 1 wire
  The device did not respond for more than 5 ms during reading, in 5 times.
• Causes: Defective connector cable or poor contact in the connector. Defective outer temperature sensor 1. Defective engine PWB.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Outer temperature sensor 1 and front PWB (YC16) Front PWB (YC2) and engine PWB (YC10)
  Defective outer temperature sensor 1. Replace outer temperature sensor 1.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7901
• Description: Drum K EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector. Defective drum PWB K.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum PWB K and front PWB (YC7) Front PWB (YC2) and engine PWB (YC10)
  Defective drum PWB K. Replace the drum unit K.

• Code: 7902
• Description: Drum C EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector. Defective drum PWB C.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum PWB C and front PWB (YC12) Front PWB (YC2) and engine PWB (YC10)
  Defective drum PWB C. Replace the drum unit C.

• Code: 7903
• Description: Drum M EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector. Defective drum PWB M.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum PWB M and front PWB (YC10) Front PWB (YC2) and engine PWB (YC10)
  Defective drum PWB M. Replace the drum unit M.

• Code: 7904
• Description: Drum Y EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector. Defective drum PWB Y.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum PWB Y and front PWB (YC14) Front PWB (YC2) and engine PWB (YC10)
  Defective drum PWB Y. Replace the drum unit Y.