What is Hitachi ZX870-5A (HCMC) Fault Code 13311-3?

Fault Code 13311-3 indicates a hydraulic pump 1 pressure sensor circuit malfunction or abnormal voltage signal detected by the Engine Control Module (ECM). This diagnostic trouble code specifically relates to the main hydraulic pump's pressure monitoring system, which continuously feeds real-time pressure data to the machine's electronic control unit.

On the Hitachi ZX870-5A (HCMC) model, this sensor plays a critical role in optimizing pump displacement, preventing system over-pressurization, and enabling the load-sensing hydraulic system to operate efficiently. When this code triggers, the ECM may enter a protective derate mode, limiting hydraulic performance to prevent potential damage to pumps, motors, or control valves. For used excavators, this fault often stems from environmental exposure causing sensor degradation or wiring harness damage from years of vibration and heat cycling.

Common Symptoms

• Hydraulic performance warning light illuminated on the operator display panel
• Noticeable loss of hydraulic power or sluggish boom/arm/bucket movements
• Intermittent derate mode where engine RPM is automatically limited to approximately 1,500 RPM
• Erratic hydraulic responses or jerky control during combined multi-function operations
• Abnormal pressure readings displayed on the monitor (if equipped), showing zero or maximum values regardless of actual system load

Potential Causes

The most common technical causes for Code 13311-3 on used ZX870-5A excavators include:

• Hydraulic pump pressure sensor failure due to internal diaphragm rupture or sensing element degradation (common after 8,000+ operating hours)
• Corroded or damaged sensor connector pins, particularly where the harness exits the main hydraulic pump housing
• Wiring harness chafing at known rub points near the pump mounting bracket and along the right-side frame rail
• ECM internal fault or corrupted calibration data (less common but possible on high-hour machines)
• Contaminated hydraulic oil causing sensor port blockage or membrane coating
• Voltage supply issues from the main power distribution harness or poor grounding connections

How to Troubleshoot and Fix Code 13311-3

Step 1: Visual Inspection and Connector Check Begin by inspecting the pressure sensor located on the main hydraulic pump 1 housing. Check for physical damage, oil contamination on the connector, or corrosion on pins. For used excavators, carefully inspect the entire wiring harness from the sensor to the ECM, looking for abrasion marks, cracked insulation, or previous repair attempts with electrical tape.

Step 2: Electrical Testing with Multimeter Disconnect the sensor connector and measure supply voltage at the harness side—you should see approximately 5.0V DC. Next, measure sensor resistance across the sensor terminals (typical specification: 200-500 ohms, but consult service manual). Check for short circuits to ground by measuring resistance between each sensor pin and chassis ground (should read open circuit/infinite resistance).

Step 3: Signal Testing and Software Diagnostics Reconnect the sensor and use Hitachi Dr.EX diagnostic software or compatible scan tool to monitor live sensor voltage while the engine runs at idle. Normal readings typically range from 0.5V (low pressure) to 4.5V (high pressure). Erratic voltage spikes, stuck readings, or out-of-range values confirm sensor replacement is needed.

Step 4: Hydraulic System Verification Before replacing components, verify actual hydraulic system pressure using a mechanical test gauge installed at the pump test port. This confirms whether the issue is electrical/sensor-related or indicates actual hydraulic problems. On used machines, also drain a hydraulic oil sample to check for contamination that might affect sensor operation.

Step 5: Component Replacement and Calibration Replace the hydraulic pump pressure sensor with genuine Hitachi parts (OEM part number recommended for proper ECM communication). After installation, clear fault codes, perform a sensor calibration procedure using diagnostic software, and conduct a complete functional test under load. Inspect and secure all harness routing to prevent future chafing.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Hitachi service manual for your specific serial number range and follow proper safety procedures. For complex electrical diagnostics or hydraulic system repairs on used excavators, professional consultation with certified Hitachi technicians is strongly recommended.