Massey Ferguson E977.03 – ECU: Engine Cooling Fan Speed Solenoid Issue

Fan control Output in short circuit (short circuit to a higher voltage source / +12V).

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

1. 1

   Check the wiring harness running from the ECU to the engine cooling fan speed solenoid for rubbed, melted, or pinched wires causing a short to power (+12V).

2. 2

   Disconnect the fan control solenoid and ECU connectors to inspect pins for corrosion, pushed-back terminals, or moisture ingress.

3. 3

   Measure the internal resistance of the fan speed solenoid to see if it reads as a dead short, indicating internal failure.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to protect the ECU/EEM from voltage spikes.

2. 2

   Access the Fan Drive

   Locate the cooling fan speed solenoid, which is typically mounted on or integrated into the electronic viscous fan drive assembly at the front of the engine.

3. 3

   Isolate the Short

   Disconnect the solenoid. Use a multimeter to test the harness side for continuity to power.

4. 4

   Repair Wiring (If Applicable)

   If the harness is shorted, splice and repair the damaged section of the wiring loom, then wrap it in high-heat protective loom.

5. 5

   Replace the Solenoid/Fan Drive (If Applicable)

   If the wiring tests good, the short is internal to the solenoid. Remove the mounting bolts securing the fan control solenoid (or the entire viscous fan clutch assembly, depending on whether the solenoid is serviceable separately) and install the new component.

6. 6

   Reassemble and Clear Codes

   Reconnect the electrical pigtail, reconnect the battery, and start the tractor. Allow the engine to reach operating temperature to verify that the fan engages properly and the E977.03 code changes to an inactive state or clears entirely.