Massey Ferguson 977.03 – EEM4 (Electronic Engine Management 4): Engine Cooling Fan Speed Solenoid Issue

Fan control output short circuit to HIGH SOURCE. The engine control module has detected that the electrical circuit controlling the electronic viscous fan clutch is shorted to a high voltage source (such as a 12V power wire or battery positive).

• 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
• 5708
• 5709
• 5710
• 5711
• 5712
• 5713

1. 1

   Inspect the wiring harness connecting the Engine ECU to the electronic viscous fan clutch for chafed, melted, or pinched wires that may be shorting to a 12V power source

2. 2

   Disconnect the fan clutch electrical connector and check for voltage on the control wire with the key ON to verify if the short is located within the tractor's wiring harness

3. 3

   Test the internal resistance of the fan clutch solenoid to determine if the clutch itself is internally shorted

4. 4

   Inspect the ECU connector pins for damage, corrosion, or bridging that could cause a short circuit at the module

1. 1

   Disconnect Power

   Disconnect the tractor's battery negative terminal before performing electrical repairs to prevent further module damage.

2. 2

   Harness Repair

   If the diagnostic tests revealed a short in the wiring harness, repair or replace the affected section of the harness and use heat-shrink tubing to seal the repair.

3. 3

   Access the Fan Clutch

   If the fan clutch solenoid is internally shorted, remove the fan shroud and relieve tension on the engine drive belts.

4. 4

   Remove the Defective Clutch

   Unplug the electrical connector. Unbolt and remove the defective viscous fan clutch assembly and fan blade from the water pump or pulley hub.

5. 5

   Install the New Part

   Transfer the fan blade to the new viscous fan clutch (if not sold as a complete assembly). Mount the new clutch to the hub and torque the bolts to OEM specifications.

6. 6

   Reassembly

   Reinstall the drive belts, fan shroud, and reconnect the electrical connector.

7. 7

   Clear Codes

   Reconnect the battery. Use the AGCO EEM4 Service Tool (or a compatible heavy-duty diagnostic scanner) to clear the inactive 000977.03 / SPN 977 FMI 3 fault code.

8. 8

   Test Operation

   Run the engine up to operating temperature and verify that the cooling fan engages properly and the fault code does not return.