• Code: E7-20
• Description: LSU laser detection error (K)
• Causes: Reduced laser power, lighting error, laser diode trouble. BD PWB trouble. Harness and connector trouble between the LD/BD PWB and the LSU cnt PWB.
• Remedy: Use SIM61-1 to check the operation of the LSU. Check the PWB and connection of the harness in the LSU. Replace the LSU.

• Code: E7-21
• Description: LSU laser detection error (C)
• Causes: Reduced laser power, lighting error, laser diode trouble. Harness and connector trouble between the LD PWB and the LSU cnt PWB.
• Remedy: Use SIM61-1 to check the operation of the LSU. Check the PWB and connection of the harness in the LSU. Replace the LSU.

• Code: E7-22
• Description: LSU laser detection error (M)
• Causes: Reduced laser power, lighting error, laser diode trouble. Harness and connector trouble between the LD PWB and the LSU cnt PWB.
• Remedy: Use SIM61-1 to check the operation of the LSU. Check the PWB and connection of the harness in the LSU. Replace the LSU.

• Code: E7-23
• Description: LSU laser detection error (Y)
• Causes: Reduced laser power, lighting error, laser diode trouble. Harness and connector trouble between the LD PWB and the LSU cnt PWB.
• Remedy: Use SIM61-1 to check the operation of the LSU. Check the PWB and connection of the harness in the LSU. Replace the LSU.

• Code: E7-28
• Description: LSU-PCU connection error
• Causes: Communication error between the CPU in the PCU PWB and the control ASIC. Improper connection of the communication connector between the PCU PWB and the LSU cnt PWB (interface PWB). Harness trouble between the PCU PWB and the LSU cnt PWB (interface PWB) PCU PWB or LSU cnt PWB (interface PWB) trouble
• Remedy: Check connection of the connector and the harness between the PCU PWB and the LSU cnt PWB (interface PWB). Replace the LSU cnt PWB. Replace the PCU PWB.

• Code: E7-29
• Description: LSU ASIC frequency error
• Causes: Oscillation abnormality of the external oscillator and the internal oscillating circuit used in the LSU ASIC. LSU ASIC abnormality on the LSU ASIC PWB.
• Remedy: Replace the LSU cnt PWB.

• Code: E7-50
• Description: Engine connection trouble
• Causes: A PWB, or firmware, or LSU which is not supported by the machine specifications is detected in the PCU PWB. PCU PWB trouble. LSU trouble.
• Remedy: Check the kind and the version of the firmware. Check the LSU, and replace it if necessary. Check the PCU PWB, and replace it if necessary.

• Code: E7-55
• Description: PWB information sum error (Engine detection)
  PCU EEPROM PWB information sum error
• Causes: PCU EEPROM sum check error. PCU EEPROM trouble. PCU EEPROM contact trouble. Malfunction due to noises
• Remedy: Replace the PCU PWB. Replace the PCU EEPROM.