Komatsu PC110-7 Fault Code S-13: Complete Diagnostic Guide

What is Komatsu PC110-7 Fault Code S-13?

Fault Code S-13 on the Komatsu PC110-7 indicates a malfunction in the swing motor parking brake solenoid circuit. This code triggers when the Engine Control Module (ECM) detects abnormal voltage or an open/short circuit in the electrical pathway controlling the swing parking brake release mechanism.

The swing parking brake system is critical for safe operation of this 11-ton excavator. When functioning properly, the solenoid valve releases hydraulic pressure to disengage the brake, allowing smooth upper structure rotation. A failure here directly impacts productivity and can create serious safety hazards on job sites, particularly on slopes or during transport operations.

Common Symptoms

Operators experiencing Code S-13 typically report:

• Swing function completely disabled or fails to activate despite engine running
• Swing motor brake refuses to release, preventing upper structure rotation
• Warning indicator illuminated on the monitor panel (brake symbol or check engine light)
• Intermittent swing operation that works briefly then locks up
• Abnormal clicking or buzzing sound from the swing motor area when attempting to rotate

Potential Causes

The most frequent technical causes for S-13 on used PC110-7 excavators include:

• Faulty swing brake solenoid coil (resistance out of specification, typically should read 20-30 ohms)
• Damaged wiring harness between the ECM and solenoid, especially at flex points near the swing bearing
• Corroded or loose electrical connectors at the solenoid or ECM junction points
• Failed relay in the swing brake control circuit
• Internal short or open circuit within the solenoid valve assembly
• ECM power supply issues affecting the 12V or 24V output to the solenoid circuit

On used machines, harness abrasion from rubbing against the swing post is particularly common due to thousands of rotation cycles.

How to Troubleshoot and Fix Code S-13

Step 1: Visual Inspection Begin by inspecting the swing motor parking brake solenoid located on the swing motor assembly. Check for physical damage, oil contamination on connectors, or signs of overheating. On used excavators, carefully trace the wiring harness from the solenoid to the main harness, looking for abrasion points, particularly where cables pass through the center joint.

Step 2: Electrical Testing Using a digital multimeter, disconnect the solenoid connector and measure coil resistance across the solenoid terminals. Compare readings against Komatsu specifications (typically 20-30 ohms at 20°C). Next, check for supply voltage at the harness connector with ignition on—you should see battery voltage when the swing function is activated.

Step 3: Circuit Continuity Check Test for continuity between the ECM connector and the solenoid harness. Check for shorts to ground on both wire circuits. Pay special attention to connector pins for corrosion—clean with electrical contact cleaner and apply dielectric grease.

Step 4: Component Replacement If resistance or voltage readings fall outside specifications, replace the faulty component. For used machines, consider replacing both the solenoid and associated connectors simultaneously, as connector degradation often accompanies solenoid failure. Clear codes using Komatsu diagnostic software (KOMTRAX or compatible scan tool) and verify repair through operational testing.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnosis for complex electrical issues or if unfamiliar with high-voltage systems.