What is Komatsu PC200LC-7 Fault Code E317?

Fault Code E317 on the Komatsu PC200LC-7 indicates a malfunction in the engine controller (ECM) communication circuit, specifically related to the CAN (Controller Area Network) communication line between the engine ECM and the monitor ECM. This code is triggered when the data transmission between these two critical control units is interrupted, delayed, or corrupted beyond acceptable parameters.

The CAN communication system is essential for the PC200LC-7's integrated control architecture. The engine ECM manages fuel injection, timing, and emissions control, while the monitor ECM handles operator displays, warning systems, and data logging. When communication fails, the machine cannot properly coordinate these systems, potentially leading to performance degradation, inaccurate gauge readings, and safety concerns. For used excavators, this fault often stems from age-related deterioration of wiring harnesses or connector corrosion rather than internal ECM failure.

Common Symptoms

• Warning light illuminated on the instrument cluster, often accompanied by a communication error message on the monitor display
• Erratic or frozen gauge readings, including engine RPM, coolant temperature, or fuel level showing incorrect or non-updating values
• Intermittent loss of engine control, with possible unexpected derate or engine shutdown protection modes activating
• Multiple fault codes appearing simultaneously, as the monitor ECM cannot properly interpret signals from other systems
• Difficulty starting or prolonged cranking time due to improper fuel system initialization

Potential Causes

Damaged CAN communication wiring harness is the most common culprit in used PC200LC-7 excavators. The harness routing near the engine bay experiences significant vibration and heat exposure, causing insulation breakdown or wire fractures. Pay special attention to areas where the harness contacts the engine block or passes through metal grommets.

Corroded or loose connector pins at either the engine ECM (located behind the cab on the right side) or monitor ECM (typically under the operator's seat). The PC200LC-7's connector design is susceptible to moisture intrusion, especially in machines with compromised weatherproofing seals.

Faulty termination resistors on the CAN bus network can cause signal reflection and communication errors. These 120-ohm resistors are located at each end of the CAN bus.

ECM internal failure (less common) where the communication module within either controller has failed. This typically occurs only after severe electrical events or water damage.

Voltage supply issues to either ECM, including poor ground connections or intermittent battery power delivery through corroded main power cables.

How to Troubleshoot and Fix Code E317

Step 1: Visual Inspection and Connector Verification Begin by inspecting the CAN communication harness routing from the engine ECM to the monitor ECM. On used excavators, look specifically for harness wear points where cables contact frame members, especially near the turntable junction. Disconnect both ECM connectors and carefully inspect all pins for corrosion, bent terminals, or moisture. Clean connectors with electrical contact cleaner and apply dielectric grease before reconnection. Check for proper connector lock engagement—partial connections are common on aged machines.

Step 2: Electrical Testing with Multimeter Using a digital multimeter, check for proper CAN-High and CAN-Low voltage levels. With ignition on and engine off, measure between CAN-High and ground (should read approximately 2.5V) and CAN-Low and ground (should also read approximately 2.5V). The differential voltage between CAN-High and CAN-Low should be near 0V at rest. Measure termination resistance by disconnecting both ECMs and checking resistance across CAN-High and CAN-Low terminals—you should read approximately 60 ohms (two 120-ohm resistors in parallel). Deviations indicate open circuits or failed termination resistors.

Step 3: Advanced Diagnostics and Repair Connect Komatsu diagnostic software (KOMTRAX Plus or equivalent) to monitor real-time CAN bus traffic and identify whether the engine ECM or monitor ECM is failing to transmit. For used excavators with high operating hours, consider replacing the entire CAN harness section rather than attempting repairs, as age-related insulation failure often affects multiple points. If electrical testing confirms proper wiring but the fault persists, ECM replacement may be necessary—always update the replacement ECM with the latest firmware. Clear codes after repairs and perform a full operational test cycle.

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Disclaimer: This guide provides general troubleshooting information for the Komatsu PC200LC-7. Always consult the official service manual and consider professional diagnostic services for complex electrical issues. Improper repairs may cause further damage or safety hazards.