KUKA KSS00402 Resolver Error – Causes, Symptoms & How to Fix

Error Code Overview

• Error Code: KSS00402
• Category: Servo / Feedback System
• Severity: High
• System: KRC4 / KSP Drives
• Impact: axis motion disabled, robot cannot operate properly

Quick Fix for KUKA KSS00402 Resolver Error

If KSS00402 (Resolver Error) occurs, perform the following immediate actions:

1. Restart the KRC4 Controller
Perform a full system reboot to clear temporary faults.
Power off → wait at least 10 seconds → poweron.

2. Power Cycle the Robot and Servo Drives
Shut down and restart the robot system and KSP drives to reset transient feedback errors.

3. Inspect Resolver Cables and Connectors
Check resolver feedback cables for:

• Loose or disconnected plugs
• Bent or damaged pins
• Signs of corrosion or wear

4. Check Servo Motor and Feedback Connections
Verify that all motor and encoder/resolver connectors are securely seated and correctly wired.

5. Reduce Electrical Noise (EMI) and Improve Grounding
Minimize interference affecting resolver signals:

• Route power cables away from resolver/feedback lines
• Ensure proper cabinet grounding
• Verify shielding integrity of feedback cables

These actions may restore operation if the fault is caused by loose connections, electrical noise (EMI), or temporary feedback signal disturbances.

What Is KUKA KSS00402 Resolver Error?

KSS00402 indicates a resolver feedback fault in a KSP servo drive.
The resolver provides rotor position feedback to the drive controller; without it:

• axis stops or refuses to move
• Robot cannot initialize affected axis
• Fault may propagate to connected axes

Real-World Example:
Observedon KUKA KSP 600-3x20 (00-198-265) when resolver cable insulation degraded after vibration exposure.

Common Symptoms

• Robot axis frozen or not moving
• KSP servo drive alarm in SmartHMI
• Red or blinking LEDon affected KSP module
• Unexpected stops during operation
• HMI shows “KSS00402 Resolver Error”

Users may search with:

• KUKA axis not moving
• KUKA resolver fault
• KRC4 servo feedback error

Common Causes of KSS00402

1. Resolver Cable or Connector Fault

• Loose, bent, or pinched wiring
• Corrosionon connector pins
• Poor grounding or shielding

2. Servo Drive (KSP) Fault

• Internal electronics failure
• Overheating of resolver interface
• I/O module malfunction

3. Electrical Noise / EMI

• Nearby high-current power cables
• EMI from drives or power supply
• Improper cabinet grounding

4. Motor / Resolver Fault

• Resolver inside motor damaged
• Worn bearings causing misalignment
• Mechanical shock affecting resolver

5. System Configuration / Firmware

• Mismatched KRC4 & KSP firmware
• Improper drive initialization sequence
• Parameter corruption

💡 Model-Specific Insight:
Frequently occurson KSP 600-3x20 (00-198-265) and KSP 400-10 (00-204-132) when cables are aged or motor subjected to vibration.

KSS00402 Replacement Components

• KUKA KSP servo drive module
• Resolver feedback cables & connectors
• Servo motor with integrated resolver(if hardware damaged)
• Shielded wiring & grounding components

⚠️ Compatibility Note:
Verify KSP module type and axis number before replacing resolver or drive.

Need a replacement? Check availability and specifications in our [KUKA KSP & KPP Drive Series] inventory.

Quick Diagnostic Flow

1. Check Resolver Cable
   → Loose/damaged → reseat or replace
2. Check KSP Module LED
   → Red / blinking → test driveon another axis
3. Test Motor / Resolver
   → Measure resistance & signal output
   → Confirm rotor alignment
4. Reduce EMI / Noise
   → Re-route high-current cables
   → Verify grounding & shielding
5. Check System Configuration
   → Match firmware versions
   → Re-initialize drive parameters
6. Replace Faulty Components
   → Confirm resolver or KSP hardware defect
   → Reboot and test axis motion

💡 Software vs Hardware Tip:
Verify CCU communication; a CCU fault can mimic resolver errors, triggering KSS00402 even when resolver & drive are fine.

How to Troubleshoot KUKA KSS00402

Step 1 – Inspect Resolver Cable

• Check connectors for bent pins, corrosion, or loose seating

Step 2 – Check Servo Drive (KSP)

• Observe LED indicators
• Swap with known good module if possible

Step 3 – Test Motor / Resolver

• Measure resolver resistance & output signals
• Confirm proper rotor alignment

Step 4 – Reduce Electrical Noise

• Reroute cables, verify grounding and shielding

Step 5 – System Configuration Check

• Confirm firmware match between KRC4 & KSP
• Re-initialize drive parameters if needed

Step 6 – Replace Faulty Components

• Replace resolver or KSP if confirmed hardware issue
• Reboot and retest axis motion

Pro Diagnostic Tip for KUKA KSS00402

• Use SmartHMI → Drive Diagnostics → axis Feedback
• Monitor resolver signals in real-time
• Compare readings with adjacent axes
• Use oscilloscope for detailed waveform analys is
• Log errors to identify intermittent faults

Prevention & Maintenance

• Inspect resolver cables/connectors regularly
• Maintain proper cable routing & shielding
• Keep drive & motor temperatures within spec
• Replace aging motors / KSP modules proactively
• Avoid excessive vibration or mechanical shock

💡 Inspection Cycle:

• Monthly: cable integrity & connectors
• Quarterly: drive module LED & feedback check
• Semi-annually: resolver signal waveform inspection

Related KUKA Errors

• KUKA KSS00403 Encoder Error(digital feedback failure)
• KUKA KSS00401 Motor Error(drive/motor fault)
• KUKA KSS00404 Drive Communication Error

👉 Often linked to servo feedback issues or drive initialization failures.

FAQ

What does KUKA KSS00402 mean?

Resolver fault in servo drive system, preventing proper axis motion.

Can the robot run with a resolver error?

No, the affected axis cannot move; safety may block motion.

How to fix KUKA resolver fault?

Inspect cables/connectors, check KSP drive, test resolver, replace hardware if needed.

Can EMI trigger KSS00402?

Yes, electrical noise can interfere with resolver signals, causing the error.

What model is most affected?

Frequently seenon KSP 600-3x20 (00-198-265) and KSP 400-10 (00-204-132).