Komatsu PC1250-11R Fault Code DA2QKR: Complete Diagnostic Guide

What is Komatsu PC1250-11R Fault Code DA2QKR?

Fault Code DA2QKR indicates a communication error between the Engine Control Module (ECM) and the Machine Control Module (MCM) on the Komatsu PC1250-11R excavator. This code specifically points to a CAN bus communication failure or data transmission interruption within the machine's integrated control network.

The CAN (Controller Area Network) bus serves as the central nervous system for this excavator, allowing critical systems to exchange real-time data. When communication breaks down, the ECM cannot properly coordinate with hydraulic controls, monitoring systems, and safety protocols. For the PC1250-11R—a machine designed for high-production mining and quarry applications—this fault compromises operational efficiency and can trigger protective shutdown modes to prevent equipment damage.

Common Symptoms

When Code DA2QKR is active, operators typically experience:

• Multiple warning lights illuminated simultaneously on the monitor panel, including engine and hydraulic system alerts
• Reduced engine power or automatic derate to low-idle mode, limiting machine productivity
• Erratic hydraulic response or complete loss of certain hydraulic functions due to control signal interruption
• Intermittent gauge failures where monitor displays show incorrect readings or go blank
• Engine shutdown in severe cases, particularly when the system cannot verify safe operating parameters

Potential Causes

The most common technical failures triggering DA2QKR on used PC1250-11R excavators include:

• CAN bus wiring harness damage from vibration, particularly at flex points near the engine mount and cab pivot areas
• Corroded or loose connector pins at the ECM or MCM connection points, especially on machines operating in wet or corrosive environments
• Failed termination resistors within the CAN network (120-ohm resistors at network endpoints)
• ECM or MCM internal failure, though less common than wiring issues on used equipment
• Voltage supply problems affecting module power, often from aging battery cables or poor ground connections
• Previous repair interference where aftermarket harnesses or improper splicing created resistance points

How to Troubleshoot and Fix Code DA2QKR

Step 1: Visual Inspection Begin with a thorough physical examination of the CAN bus harness. On the PC1250-11R, trace the twisted-pair communication wires from the ECM (located near the engine) to the MCM (typically in the cab area). Look for chafing points where harnesses contact the frame, particularly around the swing bearing area. Check all connectors for corrosion, bent pins, or moisture intrusion—common issues on used excavators with 5,000+ operating hours.

Step 2: Electrical Testing Using a digital multimeter, measure CAN-High and CAN-Low voltage at the ECM connector with the key on, engine off. You should read approximately 2.5V on each line at rest. Check termination resistance by measuring between CAN-High and CAN-Low with modules disconnected—you should read 60 ohms (two 120-ohm resistors in parallel). Deviation indicates resistor failure or wiring breaks.

Step 3: Advanced Diagnostics Connect Komatsu KOMTRAX or PC-compatible diagnostic software to read real-time CAN bus traffic. Monitor for communication dropouts or error frames. Test voltage supply to both modules—verify clean 24V DC power and solid ground connections. For used machines, pay special attention to ground strap condition between engine block and frame, as corrosion here creates communication failures.

Step 4: Component Replacement If wiring and connections test properly, suspect module failure. Replace the ECM or MCM only after confirming proper power, ground, and CAN network integrity. Always clear codes and perform a complete system relearn after repairs.

---

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues. Improper repairs can cause additional system damage.