What is Komatsu PC110-8M0 Fault Code DAFGMC?

Fault Code DAFGMC on the Komatsu PC110-8M0 excavator indicates a Data Link Communication Error between the engine ECM (Engine Control Module) and the machine's main controller or monitor panel. This code signals that critical operational data cannot be properly transmitted between control systems, preventing the machine from operating at full capacity or displaying accurate operational parameters.

This communication fault is particularly critical for the PC110-8M0 because this model relies on continuous digital communication between the engine controller and the hydraulic management system. When this data link fails, the machine cannot properly coordinate fuel delivery, hydraulic pump output, and operational mode selections. The CAN bus (Controller Area Network) communication failure prevents the excavator from optimizing performance based on real-time load conditions, potentially leading to reduced productivity and increased fuel consumption.

Common Symptoms

When DAFGMC is active on your Komatsu PC110-8M0, you'll typically experience:

• Monitor panel displays "Communication Error" or shows dashes instead of engine RPM, coolant temperature, or hydraulic oil temperature readings
• Engine may run in default/limp mode with reduced power output (typically limited to 1500-1800 RPM)
• Hydraulic functions respond sluggishly or fail to automatically adjust to load conditions
• Warning lights illuminate simultaneously on the dash, including check engine and system malfunction indicators
• Inability to change operational modes (e.g., cannot switch between power modes or economy settings)

Potential Causes

For used PC110-8M0 excavators, this communication fault typically stems from:

• Damaged or corroded CAN bus wiring harness, especially at pinch points near the engine mounting brackets or swing bearing area where vibration and movement cause wire chafing
• Loose or oxidized connector pins at the ECM harness connection (20-pin or 38-pin main connector depending on production year) or at the monitor panel connection
• Failed termination resistors on the CAN bus network (120-ohm resistors at network endpoints)
• ECM internal communication circuit failure due to voltage spikes from jump-starting or electrical system issues common in aging machines
• Aftermarket monitor panel installations or previous electrical modifications that disrupted the original CAN bus architecture
• Corroded grounding points for the communication system, particularly ground G201 located near the battery box

How to Troubleshoot and Fix Code DAFGMC

Step 1: Visual Inspection of Communication Harness Begin with a thorough physical inspection of the main wiring harness running from the engine ECM to the cab. On used PC110-8M0s, check the harness routing along the right-hand side frame rail where it crosses near hydraulic lines—this is a known rub point. Look for abraded wire insulation, green corrosion on copper conductors, or evidence of previous repairs with electrical tape. Inspect all connector housings for cracks, moisture intrusion, or bent pins.

Step 2: Test CAN Bus Integrity Using a digital multimeter set to ohms, disconnect power and measure resistance between the CAN-H (High) and CAN-L (Low) pins at the ECM connector (typically pins 26 and 18 on the PC110-8M0). You should read approximately 60 ohms with both controllers connected (two 120-ohm termination resistors in parallel). If you read open circuit (OL) or extremely high resistance, you have a break in the CAN bus wiring. If you read near zero ohms, there's a short circuit in the communication lines.

Step 3: Check Communication Circuit Voltage Reconnect the harness and power up the machine to accessory mode (key on, engine off). Using a multimeter or oscilloscope, backprobe the CAN-H and CAN-L wires. With the key on, you should see approximately 2.5V DC on both lines at rest. During communication attempts (crank the engine briefly), voltage should fluctuate between roughly 1.5V and 3.5V in digital pulses. No voltage change indicates a failed ECM communication circuit or complete harness failure.

Step 4: Clean and Secure All Connections For used excavators, connector corrosion is extremely common. Remove each connector in the communication circuit, spray with electrical contact cleaner, and inspect pins for discoloration. Pay special attention to the ECM main connector and the cab-mounted display connector. Apply dielectric grease to all pins before reconnecting to prevent future corrosion. Ensure all connector locks properly engage—worn connector housings on older machines often allow partial connections.

Step 5: Verify Ground Circuits Communication errors frequently result from poor grounding. Locate and clean ground point G201 (typically a bolt near the battery tray) and ground G301 (usually on the engine block near the ECM mounting bracket). Remove the grounding bolts, wire-brush both the terminal lugs and mounting surfaces to bare metal, then reinstall with star washers to ensure solid electrical contact.

Step 6: Diagnostic Software Verification If available, connect Komatsu KOMTRAX or PC-compatible diagnostic software to the machine's diagnostic port. This allows you to monitor real-time CAN bus traffic and identify which specific controller is failing to communicate. The software will show active/inactive nodes on the network, helping pinpoint whether the ECM or monitor panel is the non-responsive component.

Critical Considerations for Used Excavators: Before replacing expensive controllers, remember that on machines with 5,000+ operating hours, harness fatigue and connection degradation cause 70-80% of communication faults. Thoroughly verify all wiring and connections before ordering parts. Check service records for previous electrical issues or amateur repairs that may have compromised the CAN bus network integrity.

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Disclaimer: This guide provides general troubleshooting information for the Komatsu PC110-8M0. Always consult the official Komatsu service manual for your specific machine serial number and production year. If you're unfamiliar with electrical diagnostics or CAN bus systems, consult a certified Komatsu technician to prevent further damage to electronic control systems.