What is Komatsu PC210LC-8 Fault Code DAFGMC?

Fault Code DAFGMC on the Komatsu PC210LC-8 indicates a communication error between the Engine Controller (ECM) and the Hydraulic Pump Controller (HPCU), specifically related to pump flow control matching issues. This code triggers when the excavator's electronic control system detects inconsistent data exchange between these two critical controllers, preventing proper coordination of engine output with hydraulic demand.

This fault is particularly significant on the PC210LC-8 because this model utilizes Komatsu's advanced closed-center hydraulic system with electronic load-sensing. When the ECM and HPCU cannot properly communicate, the machine loses its ability to optimize fuel efficiency and match hydraulic flow to operational demands. This communication failure directly impacts the excavator's performance, potentially causing rough operation, reduced productivity, and increased fuel consumption.

Common Symptoms

• Erratic hydraulic response during combined operations (boom and swing simultaneously), with noticeable hesitation or surging
• Engine RPM fluctuations under load, particularly when operating multiple hydraulic functions
• Reduced digging force and slower cycle times, even at full throttle settings
• Monitor panel warning light activation (typically the action/caution lamp flashing)
• Intermittent power derate where the machine suddenly loses power before recovering

Potential Causes

The DAFGMC code typically results from specific issues common in used PC210LC-8 excavators:

• CAN bus wiring harness damage between the engine compartment and operator cab, especially at the harness routing point near the right-hand swing bearing where vibration causes wire chafing
• Corroded connector pins on the 24-pin HPCU connector (located under the operator platform) due to water intrusion from worn floor seals
• Failed HPCU relay in the main fuse/relay box, which disrupts controller power supply
• ECM internal communication module failure, more common in machines with over 8,000 operating hours
• Low battery voltage (below 22 volts on this 24V system) causing intermittent controller resets
• Outdated ECM or HPCU software, particularly on early 2008-2009 production units

How to Troubleshoot and Fix Code DAFGMC

Step 1: Initial Verification and Data Collection Connect Komatsu KOMTRAX diagnostic software or an aftermarket tool compatible with KOMTRAX Plus systems. Record all active and pending codes, and check the freeze frame data for voltage levels when the code set. Verify battery voltage with a multimeter—it should read 24-28 volts with the engine running.

Step 2: Physical Harness and Connector Inspection Inspect the CAN bus harness routing from the ECM (located behind the right-hand side panel) to the HPCU (under the cab floor). On used excavators, pay special attention to the harness section crossing the swing bearing area—this is a known rub point. Check for wire insulation damage, exposed copper, or repairs with electrical tape. Remove and inspect both the ECM and HPCU connectors for bent pins, corrosion, or moisture. Clean with electrical contact cleaner and apply dielectric grease.

Step 3: Electrical Testing With the key ON, engine OFF, measure CAN-High and CAN-Low voltage at the HPCU connector (refer to the PC210LC-8 service manual for specific pin locations—typically pins 16 and 17). You should see approximately 2.5V on CAN-High and 2.5V on CAN-Low at rest. Using a 120-ohm terminating resistor test, verify proper CAN bus termination resistance between the two wires (should read 60 ohms with both controllers connected).

Step 4: Controller and Software Verification If wiring checks pass, test the HPCU relay in the main relay box by swapping it with an identical relay (like the starter relay). Clear codes and test operation. If the code persists, connect to Komatsu diagnostic software to verify both ECM and HPCU software versions—early PC210LC-8 models may require controller firmware updates to resolve known communication bugs.

Step 5: Component Replacement Priority For used excavators showing this code, replacement priority should be: (1) damaged harness sections, (2) corroded connectors, (3) HPCU relay, (4) HPCU controller, (5) ECM. Always address wiring issues before replacing expensive controllers, as harness problems cause 70% of communication codes on machines over 5,000 hours.

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Disclaimer: This guide provides general troubleshooting information for the Komatsu PC210LC-8. Always consult the official Komatsu service manual for your machine's specific serial number range, and consider engaging a certified Komatsu technician for complex electrical diagnostics. Improper repairs may void warranties or cause additional system damage.