Komatsu PC1250-8R Fault Code DA2SKQ: Technical Guide

What is Komatsu PC1250-8R Fault Code DA2SKQ?

Fault Code DA2SKQ indicates a communication error between the Engine Control Module (ECM) and the Hydraulic Pump Control System, specifically related to the pump displacement control circuit feedback signal. This code triggers when the ECM detects an abnormal voltage or intermittent signal from the hydraulic pump's proportional solenoid valve position sensor, which regulates pump output based on engine load and hydraulic demand.

In the PC1250-8R's sophisticated CLSS (Closed-Center Load-Sensing System), this communication is critical for fuel efficiency and coordinated power delivery. When this circuit fails, the machine cannot properly match hydraulic flow to work requirements, leading to performance degradation and potential component damage from improper pressure regulation.

Common Symptoms

• Hydraulic system derate mode – reduced pump displacement limiting swing speed, boom response, and overall cycle times
• Amber warning light on the monitor panel with "Check Engine" or hydraulic system alert displayed
• Erratic hydraulic response – inconsistent actuator speeds or jerky movements during combined functions
• Increased fuel consumption due to the ECM defaulting to conservative pump control parameters
• Error message displayed on the multifunction monitor referencing pump control or ECM communication fault

Potential Causes

The most common technical failures triggering DA2SKQ on used PC1250-8R excavators include:

• Damaged wiring harness at the pump mounting area where vibration and heat cause insulation breakdown (known weak point on high-hour machines)
• Corroded or loose connector at the proportional solenoid valve – moisture intrusion is common in the engine compartment
• Failed proportional solenoid position sensor due to internal wear or contaminated hydraulic oil entering the sensor housing
• ECM internal fault affecting the pump control output driver circuit (less common but possible on 8,000+ hour machines)
• Hydraulic contamination causing the solenoid spool to stick, preventing proper position feedback

How to Troubleshoot and Fix Code DA2SKQ

Step 1: Visual Inspection Using Komatsu KOMTRAX or diagnostic laptop with VCMS software, confirm code status. Inspect the main pump harness routing from the ECM (located behind the cab) to both hydraulic pumps. Check for chafing against the engine block, heat damage near exhaust components, or oil saturation indicating seal leaks.

Step 2: Electrical Testing Disconnect the 6-pin connector at the suspect pump's proportional solenoid. Using a digital multimeter, measure resistance between sensor pins (typically 20-50 ohms for the solenoid coil, 1-5k ohms for position sensor). Check for supply voltage (12-24V) at the harness connector with ignition on. Verify ground continuity to ECM (should be <1 ohm).

Step 3: Component Testing For used excavators, perform a wiggle test on all connectors while monitoring live data in diagnostic software – intermittent faults often reveal themselves. Clean connectors with electrical contact cleaner and apply dielectric grease. If readings are out of specification, replace the solenoid valve assembly (Komatsu part approximately $800-1,200). Clear codes and perform a pump calibration procedure using diagnostic software.

Disclaimer: This guide provides general troubleshooting information. Always consult Komatsu factory service manuals and qualified technicians for complex hydraulic-electronic system repairs. Improper diagnostics may cause secondary damage to expensive ECM or pump components.