Massey Ferguson 520211.31 – Engine Control Unit (ECU) / EEM4: ECU internal fault 0103 / Chip error in the CY33x power stage component 0

The CY33x is the internal injection processor/power stage chip inside the engine computer responsible for driving and monitoring the fuel injectors. FMI 31 indicates that the component has suffered an internal failure or over-temperature event.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724

1. 1

   Check system voltage to verify that the battery and alternator are providing stable voltage, as spikes or severe drops can cause the ECU to disable power stages.

2. 2

   Inspect ECU main power relays for sticking, short circuits, or corrosion.

3. 3

   Test the engine wiring harness leading to the fuel injectors for chafed wires causing a short-to-ground or short-to-power, which could overload and burn out the ECU's internal power stage.

4. 4

   Use an AGCO diagnostic tool (WinEEM3/4) to clear the code and cycle the key. If the code immediately returns, the ECU has suffered a permanent internal hardware failure.

1. 1

   Disconnect battery

   Disconnect the tractor's battery (negative terminal first) to prevent electrical arcing.

2. 2

   Locate ECU

   Locate the EEM4 Engine ECU on the engine block.

3. 3

   Unplug ECU

   Carefully release the locking levers on the main wiring harness connectors and unplug them from the ECU.

4. 4

   Remove ECU

   Unbolt the ECU from its vibration-isolating mounting bracket and remove it from the machine.

5. 5

   Install replacement ECU

   Install the replacement EEM4 ECU and torque the mounting bolts to OEM spec.

6. 6

   Reconnect wiring harnesses

   Reconnect the wiring harnesses, ensuring the locking levers are fully seated.

7. 7

   Reconnect battery

   Reconnect the battery.

8. 8

   Program new ECU

   A new or remanufactured ECU will be blank or lack the specific dataset for your tractor. You must connect the AGCO Electronic Diagnostic Tool (EDT) / WinEEM4 software to flash the ECU with the correct engine variant and dataset matching the tractor's serial number.