What is Komatsu PC220-8M0 Fault Code DAZQKR?

Fault Code DAZQKR on the Komatsu PC220-8M0 indicates a communication error between the machine's Engine Control Module (ECM) and the hydraulic system controller, specifically related to the pump flow control circuit.

This diagnostic trouble code signals that the ECM is unable to receive or verify data from the hydraulic pump's electronic control system. The Komatsu PC220-8M0 utilizes an advanced closed-loop hydraulic system where the engine controller and pump controller must constantly communicate to optimize fuel efficiency and hydraulic performance. When this communication fails, the machine's ability to match engine power with hydraulic demand is compromised, leading to reduced productivity and potential component stress. This is particularly critical on the PC220-8M0 model, which relies heavily on integrated electronic controls for its CLSS (Closed-Load Sensing System) hydraulics.

Common Symptoms

When fault code DAZQKR is active, operators typically experience:

• Warning light illumination on the instrument cluster, often accompanied by a wrench or diagnostic icon
• Reduced hydraulic response or sluggish boom/arm movements, especially under load
• Engine derate mode where maximum RPM is limited to protect components
• Intermittent loss of fine control during precision work, with jerky or inconsistent hydraulic operation
• Increased fuel consumption due to improper engine-pump matching

Potential Causes

The most common technical reasons for DAZQKR appearing on used Komatsu PC220-8M0 excavators include:

• Corroded or loose wiring connectors between the ECM and hydraulic pump controller (known issue at the main harness junction near the pump)
• Damaged CAN bus wiring due to rubbing against the pump mounting bracket—a common wear point on machines with 4,000+ hours
• Failed pump solenoid controller or internal circuit board degradation from heat and vibration exposure
• ECM software glitches requiring calibration updates or memory corruption from voltage spikes
• Ground circuit failure at chassis grounding points, especially where corrosion accumulates on used machines
• Hydraulic oil contamination causing proportional solenoid valve sticking, preventing proper signal response

How to Troubleshoot and Fix Code DAZQKR

Step 1: Visual Inspection of Harness and Connectors Begin by inspecting the main wiring harness running from the cab-mounted ECM to the hydraulic pump. On used excavators, check for harness abrasion points where cables contact the pump housing or cross-members. Disconnect the pump controller connector (typically a 14-pin Deutsch connector) and inspect pins for corrosion, bent contacts, or moisture intrusion. Clean contacts with electrical cleaner and apply dielectric grease.

Step 2: Test CAN Bus Communication Circuits Using a digital multimeter, check the CAN-High and CAN-Low lines between the ECM and pump controller. With ignition on but engine off, measure voltage between CAN-High and ground (should read approximately 2.5-3.5V) and CAN-Low to ground (should read 1.5-2.5V). Check termination resistance between CAN-High and CAN-Low with power off—should measure 60 ohms if termination resistors are intact.

Step 3: Verify Ground Circuits and Power Supply Inspect all chassis ground points near the hydraulic pump and ECM mounting locations. On used machines, corrosion at ground straps is extremely common. Clean grounding surfaces to bare metal and verify continuity. Check pump controller power supply voltage—should be stable 24V DC with engine running.

Step 4: Advanced Diagnostics with Komatsu Software Connect Komatsu diagnostic software (KOMTRAX or PC Service Tool) to access real-time communication data. Monitor the pump controller response rate and verify bidirectional communication. For used excavators with aftermarket repairs, verify that controller software versions are compatible—mismatched firmware can cause communication faults.

Step 5: Component Testing and Replacement If harness and communication tests pass, test the proportional control solenoids on the hydraulic pump. Measure solenoid resistance (typically 8-12 ohms) and check for mechanical binding. Consider that on high-hour used machines, internal controller board failures are common and may require pump controller replacement rather than full pump assembly.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Komatsu service manual for your specific machine serial number. If you lack proper diagnostic tools or experience with high-voltage systems, seek professional assistance from a certified Komatsu technician.