JCB U010A – ECU: Lost Communication With Exhaust Gas Recirculation Control Module 'A'

The Engine Control Unit (ECU) has lost its CAN bus communication link with the Exhaust Gas Recirculation (EGR) Control Module 'A'. This indicates a failure in the communication line, which is typically caused by electrical issues such as a wiring fault, a blown fuse, or a malfunctioning control module. When this communication is lost, the EGR system becomes non-functional and the engine's performance may be affected, potentially forcing the machine into a reduced power limp mode.

• 3CX
• 4CX
• Loadall
• JS205
• JS220
• BS4 engine models
• Tier 4 engine models

1. 1

   Visually inspect the wiring harness and connectors between the Engine ECU and the EGR valve actuator for chafing, corrosion, or loose connections.

2. 2

   Check the main engine connector (the 'rocket connector' on BS4 engines) to ensure it is securely fastened, alignment marks match, and there are no pushed-back or recessed pins.

3. 3

   Use a diagnostic scanner to check for other active or stored fault codes, such as CAN bus errors (e.g., U040B) or power supply issues.

4. 4

   With the ignition off, disconnect the electrical connector from the EGR valve actuator. Then, with the ignition on, verify a 12V power supply and a good ground connection at the EGR actuator connector pins.

5. 5

   Inspect the relevant fuses for the engine and EGR system.

6. 6

   With the ignition off, perform a CAN bus circuit integrity check by measuring resistance between CAN High and CAN Low at the EGR actuator connector (a healthy bus reads approximately 60 Ohms; 120 Ohms indicates a missing terminating resistor or broken line). Also check for short circuits between the CAN lines and to power or ground.

1. 1

   Address connection issues

   Securely reconnect any loose or improperly seated connectors, ensuring proper alignment. Repair or replace any damaged wiring or corroded terminals found during inspection.

2. 2

   Resolve power or ground faults

   If a lack of power or ground to the EGR actuator was identified, trace the circuit back to its source to replace a blown fuse, repair a broken wire, or clean a corroded ground point.

3. 3

   Clear codes and re-test

   After performing wiring or connection repairs, clear the fault codes using a diagnostic scanner. Start the machine and operate it to see if the U010A fault code returns.

4. 4

   Replace EGR actuator

   If wiring, connectors, power, and ground are all confirmed good and the fault persists, replace the EGR valve actuator. Disconnect the electrical connector and remove the old actuator from the EGR valve body. Install the new actuator, ensuring it is correctly seated and mounting hardware is tightened to manufacturer specifications, then reconnect the electrical connector.

5. 5

   Calibrate new actuator

   Perform a calibration or 'learning' procedure using JCB ServiceMaster software so the Engine ECU can learn the position and range of motion of the new EGR actuator.

6. 6

   Final system check

   Clear any remaining fault codes and perform a final operational check of the machine to ensure the issue is resolved and engine performance has returned to normal.