What is Sumitomo SH80-6B Fault Code P1243-3?

Fault Code P1243-3 on the Sumitomo SH80-6B excavator indicates a Turbocharger Wastegate Control Solenoid Circuit malfunction with a moderately severe severity level. This code is triggered when the Engine Control Module (ECM) detects an abnormal electrical signal or improper operation within the wastegate control circuit, specifically related to voltage irregularities or response failures.

The wastegate solenoid regulates boost pressure by controlling exhaust gas flow through the turbocharger. On the SH80-6B's diesel engine, precise boost control is critical for maintaining proper air-fuel ratios, preventing over-boosting, and ensuring optimal hydraulic pump performance. When this system fails, the ECM cannot properly modulate turbocharger output, directly impacting the machine's power delivery and fuel efficiency.

Common Symptoms

• Check Engine Light illuminated on the instrument panel with possible power derate mode activated
• Noticeable loss of engine power during high-load operations like digging or lifting heavy buckets
• Black smoke from the exhaust indicating improper combustion due to unregulated boost pressure
• Turbocharger overboost or underboost conditions causing erratic engine performance
• Increased fuel consumption as the ECM attempts to compensate for boost pressure irregularities

Potential Causes

The P1243-3 code on used SH80-6B excavators typically stems from age-related electrical and mechanical wear:

• Corroded or damaged wiring harness connections at the wastegate solenoid (common rub point near the turbocharger heat shield)
• Failed wastegate control solenoid due to carbon buildup, internal coil failure, or mechanical sticking
• ECM internal circuit failure affecting the solenoid driver circuit
• Damaged or chafed wiring along the engine bay routing path, especially where harnesses contact frame rails
• Poor ground connections at the engine block causing voltage reference issues
• Connector pin corrosion from moisture intrusion in older machines

How to Troubleshoot and Fix Code P1243-3

Step 1: Visual Inspection Begin with a thorough inspection of the wastegate solenoid wiring harness from the ECM to the solenoid. On used excavators, check for wire chafing against the turbocharger heat shield, cracked insulation, or corroded connector pins. Clean all connectors with electrical contact cleaner and apply dielectric grease.

Step 2: Electrical Testing Using a digital multimeter, disconnect the wastegate solenoid connector and measure resistance across the solenoid terminals (typically 10-30 ohms for most solenoids—verify with Sumitomo specifications). Test for voltage supply at the harness connector with the ignition on (should read battery voltage). Check for proper ground continuity to the engine block (less than 1 ohm resistance).

Step 3: Solenoid Function Test With Sumitomo diagnostic software or a compatible scan tool, perform an active test to command the wastegate solenoid on/off while monitoring response. Listen for audible clicking at the solenoid. If no response occurs despite correct voltage/resistance, replace the wastegate control solenoid.

Step 4: Advanced Diagnostics If all electrical tests pass but the code persists, inspect the wastegate actuator linkage for mechanical binding or vacuum leaks in pneumatic systems. Test ECM output with an oscilloscope to verify proper pulse-width modulation signals.

Disclaimer: This guide provides general diagnostic information. Always consult the official Sumitomo service manual and consider professional assistance for complex electrical diagnostics or ECM programming on used equipment.