What is Komatsu PC200-10 Fault Code DHS4MA?

Fault Code DHS4MA on the Komatsu PC200-10 excavator indicates a malfunction in the Machine Control (MC) system's antenna communication circuit. This diagnostic trouble code specifically points to an interruption or abnormal signal between the GNSS antenna (Global Navigation Satellite System) and the machine control ECU, which is critical for grade control and semi-automatic excavation features.

The PC200-10's intelligent Machine Control system relies on continuous satellite positioning data to execute precision digging operations. When code DHS4MA appears, the MC-ECU detects either a signal loss, voltage irregularity, or complete communication failure from the roof-mounted antenna assembly. This compromises the excavator's ability to maintain accurate bucket positioning relative to programmed grade plans, making it critical to address immediately on machines equipped with factory or aftermarket guidance systems.

Common Symptoms

• Machine Control display shows "Antenna Error" or similar warning message on the monitor panel
• Loss of automatic blade/bucket control – system defaults to manual operation mode
• Intermittent or complete loss of positioning data displayed on the MC screen
• Yellow warning light illuminated on the instrument cluster (MC system indicator)
• Reduced productivity as operators cannot utilize semi-automatic grading functions

Potential Causes

The DHS4MA code typically stems from issues common in used excavators operating in harsh environments:

• Damaged antenna cable harness – particularly at flex points near the cab roof or along the boom where repetitive movement causes wire fatigue
• Corroded or loose connectors at the antenna base or ECU junction points (common after 3,000+ operating hours)
• Physical antenna damage from tree strikes, transport incidents, or jobsite impacts
• Water intrusion into sealed antenna housing or cable junction boxes
• Faulty MC-ECU internal circuitry (less common, but possible in high-hour machines)
• Inadequate grounding at antenna mounting points causing signal interference

How to Troubleshoot and Fix Code DHS4MA

Step 1: Visual Inspection Carefully examine the GNSS antenna mounted on the cab roof for physical damage, cracks, or loose mounting. Inspect the entire cable routing from antenna to ECU, checking for pinch points, abrasion damage, or harness separation at protective conduit. On used excavators, pay special attention to wear points where cables contact metal edges.

Step 2: Connector and Wiring Diagnosis Disconnect the antenna connector at both the antenna base and the MC-ECU. Inspect pins for corrosion, bent contacts, or moisture presence. Using a digital multimeter, check for continuity through each wire in the harness (should read <5 ohms resistance). Test for short circuits between wires and ground (should read open/infinite resistance).

Step 3: Power Supply Verification With ignition on, measure voltage at the antenna power supply wire (typically 12-24V DC depending on system configuration). Reference the Komatsu PC200-10 service manual for specific pin-out diagrams. Low voltage indicates potential ECU issues or upstream power supply problems.

Step 4: Component Testing If wiring tests pass, the antenna unit itself may be faulty. Substitution testing with a known-good antenna can confirm this. For used machines, antenna failures after 5,000+ hours are not uncommon due to constant vibration and environmental exposure.

Step 5: Clear Code and Verify Repair After repairs, clear the code using Komatsu KOMTRAX diagnostic software or compatible scan tools. Operate the machine through normal working cycles and verify the MC system regains full satellite lock and positioning accuracy.

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Disclaimer: This guide provides general troubleshooting information for the Komatsu PC200-10 DHS4MA fault code. Always consult the manufacturer's official service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may affect machine safety systems or void remaining warranties on used equipment.