Komatsu machinery depends on an intricate CAN (Controller Area Network) system to link its various electronic control modules (ECMs, PT controllers, monitors, etc.). When communication fails, multiple systems may throw error codes. Below are Komatsu fault codes tied to CAN disconnections, actuator errors, and signal mismatches, along with practical repair methods.

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Code DB2RKR – CAN1 Disconnection (Engine Controller)

Description: The engine controller has stopped communicating over CAN1.

Cause & Fix:

• Cause: Connector corrosion, open CAN line, or failed controller.
• Fix: Check continuity on the CAN1 wiring and inspect both 120-ohm termination resistors. Replace any damaged nodes or connectors.

Code DA2RMC – CAN Disconnection (Pump Controller Detected)

Description: Pump controller is unable to communicate on its CAN network.

Cause & Fix:

• Cause: Loss of power, interference, or bus overload.
• Fix: Verify controller power, reseat connectors, and isolate the faulty ECU if communication errors persist.

Code DAZQKR – CAN2 Disconnection (AC Controller)

Description: Communication loss between the A/C control module and other systems via CAN2.

Cause & Fix:

• Cause: Wiring damage or failed controller.
• Fix: Inspect harness routing to the AC unit. Test with a diagnostic tool to confirm CAN activity and replace the module if it remains offline.

Code DXH4KB – 1st Clutch ECMV: Short Circuit

Description: The electrohydraulic modulating valve for the 1st clutch is shorted.

Cause & Fix:

• Cause: Internal coil damage or water intrusion.
• Fix: Disconnect and test resistance; if low or zero, replace the valve. Inspect harness for chafing near the transmission.

Code DXH5KA – 2nd Clutch ECMV: Open Circuit

Description: ECM has detected an open circuit in the 2nd clutch’s electronic valve.

Cause & Fix:

• Cause: Disconnected harness or failed solenoid.
• Fix: Reconnect wiring or replace ECMV if it reads infinite resistance.

Code DXH8KB – Forward Clutch ECMV: Short Circuit

Description: A short has occurred in the forward clutch control valve circuit.

Cause & Fix:

• Cause: Coil insulation breakdown or shorted harness.
• Fix: Replace valve and reroute wiring away from heat or pinch points.

Code DWK2KB – Variable Back Pressure Solenoid: Short Circuit

Description: This solenoid, used for exhaust or hydraulic back pressure, is shorted.

Cause & Fix:

• Cause: Water in connector or burned coil.
• Fix: Replace the solenoid and seal the connector using dielectric grease to prevent repeat failures.

Code DXJ4KB – Work Equipment Lock Solenoid: Short Circuit

Description: Locking solenoid for the work equipment is drawing too much current.

Cause & Fix:

• Cause: Overheating or frayed power wire.
• Fix: Replace solenoid and test circuit amperage to ensure it stays within rated limits.

Code D8AQKR – CAN2 Disconnection (KOMTRAX)

Description: KOMTRAX module is not connected to the CAN2 network.

Cause & Fix:

• Cause: Faulty GPS module or signal converter.
• Fix: Power cycle the unit, test CAN lines, and replace the KOMTRAX module if it fails to rejoin the network.

10. Code DA2LKB – System Operating Lamp Short Circuit (Pump Controller)

Description: The lamp circuit controlled by the pump controller has shorted.

Cause & Fix:

• Cause: Burned bulb socket or direct short to frame.
• Fix: Replace lamp and repair damaged wiring or insulation.

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Technician Tip:

CAN faults often manifest as multiple, cascading errors. Always test CAN resistance (should be 60Ω across the bus) and look for grounding problems across modules.