Komatsu PC850SE-8R Fault Code DA2SKQ: Technical Guide

What is Komatsu PC850SE-8R Fault Code DA2SKQ?

Fault Code DA2SKQ indicates a communication error or data link failure between the machine's Engine Control Module (ECM) and the hydraulic system controller on the Komatsu PC850SE-8R excavator. This diagnostic trouble code specifically points to an interruption in the CAN bus communication network that coordinates engine performance with hydraulic demand.

This code is critical for the PC850SE-8R because this model relies on integrated electronic control systems to optimize fuel efficiency and hydraulic power delivery. When communication breaks down between controllers, the machine cannot properly match engine output to hydraulic load requirements, resulting in reduced operational efficiency and potential component protection modes that limit machine capability.

Common Symptoms

When fault code DA2SKQ is active, operators typically experience:

• Engine derate mode activated, limiting maximum RPM to approximately 1,500-1,800 RPM
• Hydraulic system sluggishness or reduced cycle times during digging and lifting operations
• Warning lamp illumination on the monitor panel, often accompanied by audible alerts
• Intermittent loss of auxiliary hydraulic functions or attachment control issues
• Error messages displayed on the multi-function monitor indicating communication faults

Potential Causes

The most common technical causes for DA2SKQ on used PC850SE-8R excavators include:

• CAN bus wiring harness damage from abrasion at known rub points near the engine mounting brackets and along the upper structure rotation path
• Corroded or loose connector pins at the ECM or hydraulic controller connection points, particularly the 38-pin main harness connector
• Failed termination resistors within the CAN network (typically 120-ohm resistors at network endpoints)
• ECM or hydraulic controller internal failure, though less common than wiring issues
• Voltage supply problems to either controller, often caused by deteriorated ground connections on used machines
• Water intrusion into sealed connectors from damaged harness boots or failed seals

How to Troubleshoot and Fix Code DA2SKQ

Step 1: Visual Inspection Begin with a thorough physical examination of all wiring harnesses between the engine ECM (located behind the operator cab) and the hydraulic controller. On used excavators, pay special attention to harness routing near the swing bearing and engine mounts where vibration causes wear. Check all connector boots for cracks and inspect pins for corrosion or bent contacts.

Step 2: Electrical Testing Using a digital multimeter, verify CAN-High and CAN-Low voltage levels at both the ECM and hydraulic controller connectors. With ignition on and engine off, you should measure approximately 2.5V on both lines. Check termination resistance by measuring between CAN-High and CAN-Low with controllers disconnected—you should read approximately 60 ohms (two 120-ohm resistors in parallel). Use Komatsu KOMTRAX diagnostic software or compatible scan tools to monitor real-time communication status.

Step 3: Component Testing and Repair If wiring and voltage checks pass, test ground circuit integrity at both controllers—resistance to chassis ground should be less than 1 ohm. For used machines, clean all ground connection points thoroughly and apply dielectric grease. Replace any damaged harness sections using OEM-specification shielded cable. If the fault persists after wiring repairs, controller replacement may be necessary, though this should be the last resort after confirming all communication infrastructure is sound.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and consider engaging a certified Komatsu technician for complex electrical diagnostics and repairs.