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520262.31

Massey Ferguson 520262.31 – Engine Control Unit (ECU): CY146 error 3 / Reported SPI and COM-Errors of a Cy146

Issue description

The CY146 is an internal microchip inside the Engine Control Unit (ECU) responsible for Serial Peripheral Interface (SPI) communication. FMI 31 indicates that a 'Condition Exists' or an internal fault is present. Therefore, this code means the Engine ECU has detected a fatal internal hardware communication failure.

Applies to these machines

  • 4710
  • 7724S
  • 5712SL
  • 7722S
  • 7722
  • 5713SL
  • 7720S
  • 7716
  • 7718
  • T4
  • 7715
  • 5710SL
  • 7726
  • 4708
  • 7726S
  • 4707
  • 4709
  • 5711SL
  • 7718S
  • 7719
  • 7714
  • 7716S
  • T4 (2015-2021)
  • 7720
  • Tier 4 (2015-2021)
  • 7715S
  • 7724
  • 7700 series
  • 8600 series

Check the cause

  1. Cycle the Power: Clear the fault code and cycle the ignition key. Switch the tractor off, wait at least 2 minutes for the complete ECU after-run power down to finish, and then switch it back on. Check if the error was a transient voltage glitch.

  2. Check Voltage Supply: Verify battery voltage and inspect the main ground connections to the Engine ECU. Severe undervoltage or voltage spikes can sometimes trigger false internal communication errors.

  3. Inspect Connectors: Check the ECU wiring harness connectors for water ingress, corrosion, or damaged pins that might cause a short or power interruption.

Repair steps

  1. Disconnect battery

    Disconnect the tractor's battery negative terminal.

  2. Disconnect ECU

    Locate the Engine ECU (typically mounted on the side of the engine block) and carefully disconnect the wiring harness connectors.

  3. Remove ECU

    Unbolt and remove the faulty EEM4 ECU.

  4. Install ECU

    Install the new replacement EEM4 ECU and reconnect the wiring harnesses.

  5. Reconnect battery

    Reconnect the battery.

  6. Connect diagnostic tool

    Programming Required: Turn the ignition switch to ON. Connect the AGCO EDT (Electronic Diagnostic Tool) to the tractor.

  7. Program ECU

    Follow the EDT prompts to download the EEM4 activation file from the AGCO server and flash the correct engine software to the new ECU. (Note: The new ECU will not start the tractor until it is activated and programmed with the correct software for your specific machine).

Parts you might need

(4)

  • Engine Control Unit (ECU) / Engine Control Module (ECM) - AGCO Power EEM4 Controller

    EEM4-H411

    You must order the replacement EEM4 unit directly through an AGCO dealer using your specific engine serial number. OEM documentation explicitly warns against using a used ECU from another tractor.

  • Engine Control Unit (ECU) / Engine Control Module (ECM) - AGCO Power EEM4 Controller

    EEM4-E401

    You must order the replacement EEM4 unit directly through an AGCO dealer using your specific engine serial number. OEM documentation explicitly warns against using a used ECU from another tractor.

  • Engine Control Unit (ECU) / Engine Control Module (ECM) - AGCO Power EEM4 Controller (Bosch)

    0281020170

    You must order the replacement EEM4 unit directly through an AGCO dealer using your specific engine serial number. OEM documentation explicitly warns against using a used ECU from another tractor.

  • Engine Control Unit (ECU) / Engine Control Module (ECM) - AGCO Power EEM4 Controller (AGCO)

    837073357

    You must order the replacement EEM4 unit directly through an AGCO dealer using your specific engine serial number. OEM documentation explicitly warns against using a used ECU from another tractor.

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