KUKA C4 Drive Repair: Troubleshooting KPP and KSP Fault Codes

Understanding KUKA C4 Drive Units

The KUKA C4 controller uses two types of drive units: KPP (KUKA Power Pack) and KSP (KUKA Servo Pack). These components are essential for motor control and power supply in industrial robotic systems. Like all electronic equipment, they can develop faults over time.

Common KUKA Drive Faults and How to Identify Them

Some of the most frequently reported issues with KPP and KSP modules include:

• Error messages or fault codes

• No display or power-on failure

• Phase loss

• Overcurrent or overload conditions

• Overvoltage or undervoltage

• Overheating

• Grounding issues

• Output signal loss

• Encoder errors

• Parameter misconfigurations

• Module damage

Detailed Fault Codes and Troubleshooting Steps for Kuka C4 Drive

Here are some specific KUKA C4 drive faults and how to address them:

Error Code 26032: Overload Fault (IxT) – KPP/KSP Axis

• Cause: Excessive average current due to high load on the axis.

• Solution: Reduce load or check mechanical resistance on the axis.

Error Code 26033: Ground Fault – KPP/KSP Axis

• Cause: Overcurrent due to grounding in the power circuit.

• Solution:

  • Check motor cables for shorts or damage.

  • Inspect the motor and connections.

  • Power cycle the drive (Power Off / Power On).

  • Inspect both the KSP and KPP units.

Error Code 26034: Overcurrent Fault – KPP/KSP Axis

• Cause: Short circuits or sudden current spikes beyond the KPP’s limit.

• Solution:

  • Review current logs.

  • Check the motor and cable connections.

  • Power cycle the system.

  • Inspect KPP and KSP for physical damage.

Error Code 26035: Intermediate Circuit Overvoltage – KPP/KSP Axis

• Cause: Overvoltage during robot operation, often during braking.

• Solution:

  • Check input power voltage.

  • Inspect braking resistor or chopper.

  • Reduce braking load.

  • Reboot the drive units.

Error Code 26036: Intermediate Circuit Undervoltage – KPP/KSP Axis

• Cause: Power supply drops during motion.

• Solution:

  • Check power voltage stability.

  • Inspect wiring to the intermediate circuit.

  • Reboot and test charging circuits.

Error Code 26037: Logic Circuit Overvoltage – KPP/KSP Axis

• Cause: Logic power supply exceeds 27V.

• Solution:

  • Check and adjust the 27V power supply.

  • Power cycle the controller.

  • Inspect KSP and KPP logic boards.

Error Code 26038: Logic Circuit Undervoltage – KPP/KSP Axis

• Cause: 27V power supply drops below safe level.

• Solution:

  • Test power supply and backup battery.

  • Reinitialize the drive units.

Error Code 26041: Motor Phase Loss – KPP/KSP Axis

• Cause: One or more motor phases are not detected.

• Solution:

  • Check motor cables and motor windings.

  • Restart the system and test connections.

Error Code 26042: Communication Error – KPP/KSP Axis

Cause: Bus communication failure on the controller.

• • Power cycle the system.

  • Inspect EtherCAT wiring and stack.

  • Check the CCU, KPP, and KSP components.

Final Tips for KUKA Drive Repairs

• Always record error codes and LED statuses before rebooting.

• Use ESD-safe tools and observe safety protocols.

• Replace damaged cables or modules with certified KUKA parts.

• Regular preventive maintenance reduces long-term faults.

Conclusion

Maintaining your KUKA C4 drive system—especially the KPP and KSP units—requires knowing how to interpret error codes and methodically troubleshoot faults. By following this guide, you can reduce downtime, avoid expensive repairs, and ensure the long-term performance of your robot.