What is Komatsu PC200-7 Fault Code E317?

Fault Code E317 on the Komatsu PC200-7 indicates a malfunction in the engine pre-heating system circuit, specifically related to the intake air heater relay or its control circuit. This code is triggered when the Engine Control Module (ECM) detects an abnormal voltage signal or open/short circuit in the intake air heater circuit during cold start conditions.

The intake air heater (also called a grid heater) is essential for cold-weather starting on diesel engines. When this system fails, the ECM cannot properly warm incoming air before combustion, leading to difficult starts and incomplete fuel burn. For the Komatsu SAA6D102E-2 engine found in the PC200-7, this pre-heating function is critical for emissions compliance and engine longevity, particularly in used machines where starting systems experience accelerated wear.

Common Symptoms

When Code E317 is active on your PC200-7, you may experience:

• Hard starting or failure to start in cold ambient temperatures (below 40°F/5°C)
• White or gray exhaust smoke during initial startup, indicating unburned fuel
• Engine warning lamp illuminated on the operator display panel
• Rough idle for the first several minutes after cold start
• Longer cranking times than normal before the engine fires

Potential Causes

The most common technical reasons for E317 on used PC200-7 excavators include:

• Faulty intake air heater relay (located in the engine compartment relay box) - internal contacts wear out over time
• Open circuit in the wiring harness between the ECM and heater relay, often caused by harness chafing near the battery box mounting bracket (known wear point on this model)
• Failed intake air heater element inside the intake manifold due to carbon buildup or element burnout
• Corroded or loose electrical connectors at the relay socket or ECM C2 connector (Pin 23)
• Low battery voltage during cranking preventing proper relay activation
• ECM internal driver circuit failure (less common, but possible in high-hour machines)

How to Troubleshoot and Fix Code E317

Step 1: Visual Inspection Begin by inspecting the intake air heater relay and all associated wiring. On used excavators, check for connector corrosion, particularly at the relay socket and ECM harness connectors. Examine the harness routing near the battery box and starter motor for wire chafing or insulation damage - this is a documented wear point on PC200-7 machines.

Step 2: Electrical Testing Using a digital multimeter, test battery voltage during key-on (should be 12V minimum). Check for voltage at the relay coil when the key is turned to the preheat position (approximately 5-8 seconds before cranking). Verify continuity between ECM Pin C2-23 and the relay coil terminal. Resistance should be less than 5 ohms.

Step 3: Component Testing Remove the intake air heater relay and test it with a bench power supply or swap with a known-good relay. If the relay clicks but the code persists, measure resistance across the heater element terminals (access through intake manifold) - typical resistance is 0.5-2.0 ohms. Infinite resistance indicates a burned element.

Step 4: Advanced Diagnostics Connect Komatsu diagnostic software (PCMS or Komtrax) to read freeze-frame data and verify ECM output commands. Clear the code and monitor during a cold-start cycle to confirm the fix.

For used excavators, always inspect harness integrity and connector pin tension before replacing expensive components like the ECM or complete heater assemblies.

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Disclaimer: This guide provides general troubleshooting information for Code E317. Always consult the official Komatsu PC200-7 service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may cause additional damage or safety hazards.