• Code: 7810
• Description: Short-circuited external thermistor wire external thermistor delivers 3V or more.
• Causes: Defective connector cable or poor contact in the connector.
  Defective temperature sensor.
• 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. Temperature sensor and engine PWB (YC21)
  Defective temperature sensor. Replace the temperature sensor.

• 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 eight times successively. Mismatch between writing data and reading data occurs eight times successively.
• Causes: Poor contact in the connector terminals.
  Defective drum PWB.
• Remedy: Poor contact in the connector terminals. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit (K) and drum connect PWB(YC5) drum connect PWB and engine connect PWB (YC4) Engine connect PWB and engine PWB (YC9)
  Defective drum PWB. 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 eight times successively. Mismatch between writing data and reading data occurs eight times successively.
• Causes: Poor contact in the connector terminals.
  Defective drum PWB.
• Remedy: Poor contact in the connector terminals. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit (C) and drum connect PWB(YC3) drum connect PWB and engine connect PWB (YC4) Engine connect PWB and engine PWB (YC9)
  Defective drum PWB. 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 eight times successively. Mismatch between writing data and reading data occurs eight times successively.
• Causes: Poor contact in the connector terminals.
  Defective drum PWB.
  
• Remedy: Poor contact in the connector terminals. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit (M) and drum connect PWB(YC4) drum connect PWB and engine connect PWB (YC4) Engine connect PWB and engine PWB (YC9)
  Defective drum PWB. 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 eight times successively. Mismatch between writing data and reading data occurs eight times successively.
• Causes: Poor contact in the connector terminals.
  Defective drum PWB.
• Remedy: Poor contact in the connector terminals. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit (Y) and drum connect PWB(YC2) drum connect PWB and engine connect PWB (YC4) Engine connect PWB and engine PWB (YC9)
  Defective drum PWB. Replace the drum unit Y.

• Code: 7911
• Description: Developing unit 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 eight times successively. Mismatch between writing data and reading data occurs eight times successively.
• Causes: Poor contact in the connector terminals.
  Defective developing PWB.
• Remedy: Poor contact in the connector terminals. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Developer unit (K) and drum connect PWB(YC9) drum connect PWB and engine connect PWB (YC4) Engine connect PWB and engine PWB (YC12)
  Defective developing PWB. Replace the developer unit K.

• Code: 7912
• Description: Developing unit 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 eight times successively. Mismatch between writing data and reading data occurs eight times successively.
• Causes: Poor contact in the connector terminals.
  Defective developing PWB.
• Remedy: Poor contact in the connector terminals. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Developer unit (C) and drum connect PWB(YC7) drum connect PWB and engine connect PWB (YC4) Engine connect PWB and engine PWB (YC12)
  Defective developing PWB. Replace the developer unit C.

• Code: 7913
• Description: Developing unit 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 eight times successively. Mismatch between writing data and reading data occurs eight times successively.
• Causes: Poor contact in the connector terminals.
  Defective developing PWB.
• Remedy: Poor contact in the connector terminals. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Developer unit (M) and drum connect PWB(YC8) drum connect PWB and engine connect PWB (YC4) Engine connect PWB and engine PWB (YC12)
  Defective developing PWB. Replace the developer unit M.