What is Komatsu PC210LC-8M0 Fault Code DW91KA?

Fault Code DW91KA on the Komatsu PC210LC-8M0 indicates a communication error between the main controller (ECM) and the hydraulic pump control system, specifically related to pump flow control signal abnormality. This code triggers when the Electronic Control Module (ECM) detects inconsistent or interrupted data transmission from the pump control circuit, which directly affects the machine's ability to regulate hydraulic flow and pressure.

This fault is critical for the PC210LC-8M0 because the pump flow control system is responsible for matching hydraulic output to operator demand, ensuring fuel efficiency and responsive control. When communication is compromised, the excavator may enter a protective derate mode to prevent damage to hydraulic components, significantly reducing productivity and potentially causing costly downtime on used machines where wiring and connectors have accumulated wear.

Common Symptoms

• Hydraulic system warning light illuminated on the monitor panel with fault code displayed
• Noticeably sluggish or unresponsive hydraulic functions, particularly during simultaneous multi-function operations
• Reduced engine power or automatic derate to protect the hydraulic system
• Intermittent operation where the machine functions normally, then suddenly loses hydraulic responsiveness
• Erratic pump noise or abnormal pressure variations during operation

Potential Causes

The most frequent causes of DW91KA on used PC210LC-8M0 excavators include:

• Corroded or damaged wiring harness connectors between the ECM and pump controller, especially at flex points near the pump mounting area
• Worn or broken wiring in the harness running along the main boom or through the swing bearing area (common wear point on machines with 5,000+ hours)
• Faulty pump solenoid valve or internal sensor providing inconsistent feedback signals
• ECM software glitches or outdated firmware requiring updates
• Voltage supply issues from deteriorated ground connections or weak battery voltage affecting signal quality
• Water intrusion into connectors from damaged harness boots or seal failures

How to Troubleshoot and Fix Code DW91KA

Step 1: Visual Inspection Begin with a thorough examination of the wiring harness from the ECM to the hydraulic pump controller. Look specifically for chafing at known rub points—the swing bearing pass-through and where harnesses contact the frame near the pump. Check all connector pins for corrosion, bent terminals, or moisture. On used excavators, pay special attention to connector boots that may have hardened and cracked over time.

Step 2: Electrical Testing Using a digital multimeter, check the power supply voltage to the pump controller (should be approximately 12-24V depending on circuit). Test signal wire continuity between the ECM connector (Pin 38) and the pump controller connector following the Komatsu service manual wiring diagram. Check for proper ground circuit resistance (should be less than 5 ohms). Use Komatsu diagnostic software (KOMTRAX Plus) to monitor real-time signal data and verify communication integrity.

Step 3: Component Testing If wiring checks pass, test the pump flow control solenoid resistance (typically 20-40 ohms when cold). Inspect the pump controller module for physical damage or burnt components. For used machines, consider that internal controller failures increase after 8,000 operating hours. Clear the code and perform a functional test; if the code returns immediately, suspect the controller or ECM itself.

Step 4: Resolution Repair or replace damaged harness sections using OEM-spec wire and weatherproof connectors. Apply dielectric grease to all reassembled connections. If components require replacement, ensure compatibility with the PC210LC-8M0 serial number range. After repairs, clear codes using diagnostic software and perform a complete hydraulic function test under load.

---

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and seek assistance from certified Komatsu technicians for complex diagnostics or repairs involving the ECM or hydraulic control systems.