What is Kato HD820-2 Fault Code E35?

Fault Code E35 on the Kato HD820-2 excavator indicates a malfunction in the swing motor pressure sensor circuit or an abnormal pressure reading in the swing system. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects voltage values outside the normal operating range from the swing motor pressure sensor, or when the sensor reports hydraulic pressure readings that are inconsistent with actual machine operation.

The swing motor pressure sensor is critical for monitoring hydraulic pressure during upper structure rotation. The ECM uses this data to optimize swing performance, prevent overloading, and protect the hydraulic system from damage. On used Kato HD820-2 excavators, this code becomes particularly important as aging hydraulic components and electrical connections can lead to false readings that compromise operational efficiency and potentially cause costly component failures.

Common Symptoms

When Code E35 is active on your Kato HD820-2, you may experience:

• Erratic or sluggish swing performance with inconsistent rotation speeds
• Warning light illumination on the instrument cluster, often accompanied by an audible alarm
• Swing function derate or complete loss of upper structure rotation capability
• Intermittent swing operation that works normally then suddenly stops or becomes jerky
• Error code display on the monitor panel, sometimes cycling with other hydraulic-related codes

Potential Causes

The most common technical reasons for Code E35 on used HD820-2 excavators include:

• Faulty swing motor pressure sensor due to internal component degradation or contamination from hydraulic fluid debris
• Damaged or corroded wiring harness at connector points, especially where the harness routes near the swing bearing (a known wear point on this model)
• Loose or oxidized electrical connections at the sensor connector or ECM terminals
• Hydraulic contamination causing the sensor diaphragm to stick or provide inaccurate readings
• ECM software glitches or internal ECM failure (less common but possible in high-hour machines)
• Voltage supply issues from the main power harness feeding the sensor circuit

How to Troubleshoot and Fix Code E35

Step 1: Visual Inspection Begin by inspecting the swing motor pressure sensor location and its wiring harness. On used excavators, check specifically for harness abrasion where cables pass through the swing bearing area—a common failure point on the HD820-2. Look for corroded pins, moisture intrusion, or damaged insulation at the sensor connector.

Step 2: Electrical Testing Using a digital multimeter, verify the sensor receives proper supply voltage (typically 5V reference) from the ECM. Check resistance values across the sensor terminals according to Kato specifications (consult service manual for exact values). Test signal wire continuity from the sensor back to the ECM connector, checking for opens or shorts to ground.

Step 3: Sensor Signal Testing With the ignition on and engine running, use Kato diagnostic software or a compatible scan tool to monitor live sensor data. Compare actual hydraulic pressure readings with sensor output values. A functioning sensor should show proportional voltage changes (typically 0.5-4.5V) corresponding to pressure fluctuations during swing operation.

Step 4: Component Replacement If testing reveals sensor failure, replace the swing motor pressure sensor with a genuine Kato part. Before installation on used machinery, thoroughly clean the mounting area and apply dielectric grease to connector pins to prevent future corrosion. If wiring damage is found, repair or replace the affected harness section rather than using temporary splices.

Disclaimer: This guide provides general troubleshooting information. Hydraulic systems operate under extreme pressure and require proper training and tools. Always consult the official Kato HD820-2 service manual and consider professional diagnostic assistance for complex electrical or hydraulic issues, especially on used equipment with unknown service history.