Sumitomo SH300-6 Fault Code 1113: Complete Diagnostic Guide

What is Sumitomo SH300-6 Fault Code 1113?

Fault Code 1113 on the Sumitomo SH300-6 excavator indicates a Fuel Injection Pump (FIP) Control Circuit malfunction, specifically detecting an abnormal signal from the fuel injection pump's electronic control system. This code triggers when the Engine Control Module (ECM) identifies a voltage irregularity, open circuit, or short circuit in the wiring harness connecting to the fuel injection pump actuator.

This fault is critical for the SH300-6 because the electronic fuel injection pump directly controls fuel delivery timing and volume to the engine cylinders. When this circuit malfunctions, the ECM cannot properly regulate engine power output, fuel efficiency, or emissions control. The Sumitomo SH300-6 typically uses an Isuzu 6HK1X engine, where precise fuel pump control is essential for maintaining the engine's rated 184 horsepower and meeting emissions standards.

Common Symptoms

When Code 1113 is active on your SH300-6, you may experience:

• Engine warning light illuminated on the instrument cluster with noticeable power loss
• Engine derate mode activated, limiting machine to 60-70% of normal operating RPM
• Rough idling or inconsistent engine speed, particularly during warm-up cycles
• Black smoke from the exhaust due to improper fuel atomization
• Difficulty starting the engine, especially in cold weather conditions

Potential Causes

The most common technical reasons for Code 1113 on used SH300-6 excavators include:

• Damaged wiring harness between the ECM and fuel injection pump, particularly where the harness routes near the engine block (known rub point)
• Corroded or loose connector pins at the fuel injection pump actuator plug (C-101 connector)
• Failed fuel injection pump solenoid or internal actuator malfunction
• ECM voltage supply issues, including poor ground connections at G-102 ground point
• Water intrusion into connector housings due to damaged seals on older machines
• Intermittent short circuits caused by harness insulation degradation from heat exposure

How to Troubleshoot and Fix Code 1113

Step 1: Visual Inspection Begin by inspecting the fuel injection pump wiring harness from the ECM to the pump actuator. On used excavators, check for harness chafing against the engine mounting bracket (common failure point). Disconnect the C-101 connector at the fuel injection pump and examine pins for corrosion, bent terminals, or moisture. Clean contacts with electrical contact cleaner and apply dielectric grease.

Step 2: Electrical Testing Using a digital multimeter, perform a continuity test on the harness with the connector disconnected and ignition off. Check resistance between ECM pins (typically Pin 23 and Pin 24) and the fuel pump connector—readings should be 0.5-2.0 ohms. Test for shorts to ground; resistance should exceed 10,000 ohms. Measure supply voltage at the pump connector with ignition on—should read 12-14 volts.

Step 3: Component Testing If wiring tests pass, measure the fuel injection pump actuator resistance directly at the pump terminals (disconnect harness first). Typical resistance ranges from 2-4 ohms. Values outside this range indicate actuator failure. For used machines, also inspect the ECM ground connections at the engine block, as corrosion here causes voltage irregularities.

Step 4: Advanced Diagnostics Connect Sumitomo diagnostic software (or compatible Isuzu JALTEST equipment) to monitor live data from the fuel injection pump. Observe commanded versus actual pump position—discrepancies exceeding 5% indicate mechanical pump failure rather than electrical issues.

Disclaimer: This guide provides general diagnostic procedures for Code 1113. Always consult the Sumitomo SH300-6 service manual for torque specifications and safety procedures. If you lack experience with high-pressure fuel systems or electronic diagnostics, consult a certified Sumitomo technician to prevent equipment damage or injury.