Komatsu PC850SE-8R Fault Code DA80MA: Complete Diagnostic Guide

What is Komatsu PC850SE-8R Fault Code DA80MA?

Fault Code DA80MA indicates a malfunction in the machine's hydraulic system communication circuit, specifically related to the pump control solenoid valve or its associated wiring harness. This code is triggered when the Electronic Control Module (ECM) detects an abnormal voltage signal or open/short circuit condition in the hydraulic pump pressure control system.

On the PC850SE-8R, this fault directly impacts the machine's ability to regulate hydraulic pump output pressure. The pump control solenoid modulates hydraulic flow based on operator demand and load conditions. When this circuit fails, the excavator cannot optimize fuel efficiency or maintain proper hydraulic response, potentially leading to reduced productivity and increased operating costs.

Common Symptoms

When Code DA80MA is active, operators typically experience:

• Hydraulic system derate or reduced swing/boom speed during operation
• Amber warning light illuminated on the instrument cluster with fault code display
• Erratic hydraulic response or inconsistent implement movement under load
• Increased fuel consumption due to inability to regulate pump output efficiently
• Machine may enter limp mode limiting operational capabilities to protect components

Potential Causes

The most common technical causes for DA80MA on used PC850SE-8R excavators include:

• Damaged wiring harness near the hydraulic pump mounting area (known rub point on this model)
• Failed pump control solenoid valve due to internal coil breakdown or contamination
• Corroded or loose connector pins at the solenoid or ECM interface
• Shorted circuit caused by harness chafing against frame components during boom/arm movement
• ECM internal fault (less common, but possible in high-hour machines)
• Contaminated hydraulic oil causing solenoid valve sticking or malfunction

How to Troubleshoot and Fix Code DA80MA

Step 1: Visual Inspection Begin by inspecting the pump control solenoid and its wiring harness for obvious damage. On used excavators, check for harness wear where it routes near the hydraulic pump—this is a common failure point. Look for oil contamination on connectors, which indicates seal failure.

Step 2: Electrical Testing Using a digital multimeter, measure resistance across the solenoid coil (typically 3-8 ohms for Komatsu solenoids). Check for voltage supply at the connector with ignition on (should read approximately 24V). Inspect for short to ground by measuring resistance between each wire and chassis ground (should read infinite resistance).

Step 3: Connector and Harness Verification Disconnect the solenoid connector and inspect pins for corrosion, bent contacts, or moisture intrusion. Clean with electrical contact cleaner. Perform a wiggle test on the harness while monitoring voltage to identify intermittent connections.

Step 4: Component Replacement If electrical tests confirm solenoid failure, replace with genuine Komatsu parts to ensure proper specifications. When installing, apply dielectric grease to connector pins and secure harness away from moving components using proper routing clips.

Step 5: System Verification Clear codes using Komatsu diagnostic software (KOMTRAX) or compatible scan tool. Operate machine through full hydraulic cycles and monitor for code recurrence.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnosis for complex electrical issues or if you lack proper diagnostic equipment.