Resolving Injector Faults and ECU Errors on the Volvo G930 Motor Grader

[MikePhua]

The Volvo G930 and Its Engine Platform
The Volvo G930 motor grader was introduced in the mid-2000s as part of Volvo Construction Equipment’s G900 series, designed for precision grading, road maintenance, and infrastructure development. Built with a focus on operator comfort and electronic control integration, the G930 featured a Volvo D7E diesel engine, a 7-liter inline-six powerplant known for its fuel efficiency and torque delivery. Volvo CE, headquartered in Sweden, has long emphasized emissions compliance and diagnostic accessibility, and the G930 was among the first graders to fully integrate VCADS Pro diagnostics and CAN-based electronic control units.
Symptoms of No-Start and ECU Faults
Operators encountering startup failure on the G930 often report:

• Flashing warning on the Murphy monitor, indicating “Stop Engine – Computer Damage”
  
• Multiple e-ECU fault codes, including SID 003, 004, and 005
  
• VCADS Pro unable to connect initially, preventing diagnostic access
  
• No crank or crank without ignition, depending on fault severity
  

These symptoms point to a systemic fault in the injector control circuit, often triggered by shorted injectors or corrupted ECU software.
Understanding SID Codes and Injector Logic
Volvo’s SID (Subsystem Identifier) codes correspond to specific components within the engine management system. In this case:

• SID 003–005 typically refer to injector circuits 1–3
  
• Short to high side means the injector solenoids are receiving constant voltage, preventing pulse-width modulation
  
• ECU failsafe logic disables fuel delivery to protect internal components
  

The D7E uses electronically actuated injectors controlled by the engine ECU. When one or more injectors short to the high side, the ECU halts ignition to prevent thermal damage or runaway combustion.
Diagnostic and Repair Strategy

1. Reconnect VCADS Pro with Updated Software
   Ensure the diagnostic tool is running the latest firmware. Early versions may fail to connect due to protocol mismatch.
   
2. Scan and Log All Active and Stored Faults
   Record all SID codes and FMI (Failure Mode Indicator) values. This helps isolate whether the fault is electrical, hydraulic, or software-based.
   
3. Test Injector Resistance and Voltage
   Use a multimeter to check each injector’s resistance. Normal range is typically 1.5–2.5 ohms. Anything below 1 ohm or above 5 ohms indicates a short or open circuit.
   
4. Inspect Wiring Harness and Connectors
   Look for chafed wires, corroded terminals, or loose pins near the valve cover and ECU. Moisture ingress is a common cause of high-side shorts.
   
5. Reprogram ECU if Software Fault Is Confirmed
   If fault codes indicate a software mismatch or corruption, contact Volvo’s technical support to obtain the correct flash file. Reprogramming may require a secure login and dealer-level access.
   
6. Replace Injectors if Physically Damaged
   If resistance tests confirm internal failure, replace all affected injectors. Always torque to spec and use new seals to prevent compression leaks.
   

Field Anecdotes and Practical Advice
A technician in Houston encountered a G930 that refused to start and displayed multiple injector faults. After updating VCADS Pro and scanning the ECU, he found all six injectors shorted to the high side. The issue was traced to a failed ECU software update. After reprogramming the ECU and replacing two injectors, the machine started normally.
In another case, a grader in Alberta showed similar symptoms. The operator discovered that rodents had chewed through the injector harness, causing intermittent shorts. After replacing the harness and clearing codes, the grader returned to service.
Preventive Maintenance Recommendations

• Inspect injector harness quarterly, especially in humid or rodent-prone environments
  
• Update ECU software annually, or during major service intervals
  
• Use dielectric grease on connectors to prevent corrosion
  
• Log fault codes and service actions for future reference
  
• Train operators to recognize early signs of injector failure, such as rough idle or misfire
  

Conclusion
Injector faults and ECU errors on the Volvo G930 motor grader can be resolved through systematic diagnostics, software updates, and electrical inspection. Understanding the relationship between SID codes, injector behavior, and ECU logic is essential for restoring engine function. With proper tools and informed troubleshooting, the G930 remains a reliable and precise grading machine.