Yale 522593-12 – Engine Control Unit (ECU): CANbus Communication Loss - ECU to EPR

The Engine Control Unit (ECU) has lost communication with the Electronic Pressure Regulator (EPR) / Fuel Delivery Electronic Pressure Regulator (DEPR) over the machine's CANbus network. When this code is active, the machine may experience reduced power, misfires, or fail to start.

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1. 1

   Check the 10-amp fuse associated with the EPR circuit to ensure it has not blown

2. 2

   Inspect the wiring harness and multi-pin connector at the EPR for unseated pins, corrosion, or loose connections

3. 3

   Test the CANbus circuit (CAN HI and CAN LO) for an open circuit, short to ground, or short to battery positive

4. 4

   Verify that the EPR supply and ground circuits do not have an open circuit

1. 1

   Disconnect the Battery

   Always disconnect the battery before performing electrical repairs or replacing components.

2. 2

   Repair Wiring

   If the diagnostic checks reveal an open circuit, short to ground, or short to battery voltage on the CAN HI/CAN LO lines, repair or replace the damaged section of the wiring harness.

3. 3

   Reseat Pins

   If unseated pins are found at the EPR connector, reseat them and secure the connector.

4. 4

   Replace the EPR

   If the wiring, connector, and 10-amp fuse are all in good working condition, the internal circuitry of the Electronic Pressure Regulator (EPR) has likely failed. Remove the faulty EPR/Vaporizer assembly and install the replacement unit.

5. 5

   Clear Codes and Test

   Reconnect the battery, clear the historical fault codes from the dash display, and run the machine to verify that the communication loss code does not return and full power is restored.