Resolving ECU Communication Errors on the Volvo ECR145C Excavator

[MikePhua]

Volvo ECR145C Background and Electrical Architecture
The Volvo ECR145C is a short-radius compact excavator introduced in the late 2000s, designed for urban construction, utility trenching, and confined-space earthmoving. With an operating weight around 15,000 kg and powered by a Volvo D4D diesel engine, the ECR145C combines hydraulic precision with Tier 3 emissions compliance. Its electrical system includes multiple control modules—most notably the E-ECU (Engine Electronic Control Unit) and V-ECU (Vehicle ECU)—which communicate via CAN bus protocols to manage engine performance, diagnostics, and operator interface.
Terminology Note

• E-ECU: The engine control module responsible for fuel injection, emissions, and engine diagnostics.
  
• CAN Bus: A Controller Area Network protocol used for communication between electronic modules.
  
• PSDI201-9: A fault code indicating loss of communication between the E-ECU and other systems.
  
• Harness Routing: The physical path of wiring looms through the machine’s frame and compartments.
  
• Shielding: Protective wrapping around signal wires to prevent electromagnetic interference.
  

Symptoms and Diagnostic Clues
A PSDI201-9 fault code appears on the monitor, indicating an E-ECU communication error. This typically results in:

• Loss of engine data on the display
  
• Disabled throttle control or limp mode activation
  
• Inability to access engine diagnostics
  
• Occasional stalling or failure to start
  

The error is often intermittent, suggesting a wiring fault rather than a failed ECU. The ECR145C’s harness layout is notoriously difficult to access, with key connectors buried behind panels and under the cab floor.
Common Causes and Field Observations

• Chafed or pinched wires near the swing frame or under the cab can disrupt CAN signals.
  
• Loose connectors at the E-ECU or junction box may cause intermittent faults.
  
• Water intrusion into connectors or harness sheathing can corrode terminals.
  
• Improper grounding or broken shield wires can allow signal noise to interfere with communication.
  
• Aftermarket modifications such as GPS or telematics units may tap into CAN lines and destabilize the network.
  

In Oklahoma, a technician traced a PSDI201-9 fault to a broken ground wire near the battery box. After repairing the connection and resealing the harness, the error disappeared. In British Columbia, a rental fleet manager found that repeated pressure washing had forced water into the rear harness junction, causing multiple ECU faults.
Recommended Diagnostic Procedure

• Visual inspection of all harnesses between the E-ECU and monitor
  
• Check connector pins for corrosion, bent terminals, or loose fit
  
• Use a CAN bus diagnostic tool to verify signal integrity and module response
  
• Test continuity and resistance across suspect wires, especially shielded pairs
  
• Inspect grounding points on the frame and engine block
  

If the fault persists, consider replacing the harness segment or rerouting with new shielded cable. Volvo service bulletins may offer updated routing diagrams or connector upgrades.
Preventive Measures and Long-Term Reliability

• Apply dielectric grease to all ECU connectors during service
  
• Avoid pressure washing near electrical compartments
  
• Secure harnesses with rubber grommets and vibration-resistant clamps
  
• Install moisture barriers or conduit in high-risk areas
  
• Document any aftermarket wiring changes to avoid future conflicts
  

Conclusion
The PSDI201-9 error on the Volvo ECR145C signals a breakdown in communication between the engine ECU and the machine’s control system. While the fault may seem daunting, it is often caused by wiring damage, poor grounding, or connector corrosion. With methodical diagnostics and careful harness inspection, the issue can be resolved—restoring full engine control and preventing costly downtime.