New Holland 3385 – ECM: Electromagnetic Circuit of Viscous Fan Drive - Open Circuit or Short Circuit to Ground

The engine control module (ECM) has detected an open circuit or a short circuit to ground in the electrical circuit of the electronically controlled viscous fan drive. This fault prevents proper fan operation, which can lead to engine overheating or cause the fan to run continuously at maximum speed as a fail-safe.

• TG210
• TG230
• TG255
• TG285
• T8010
• T9030
• T9040
• TJ375
• TJ380
• TJ430
• TJ500
• G170
• G210
• 8670
• 8770
• 8870

1. 1

   Carefully inspect the wiring harness leading to the viscous fan clutch solenoid for any signs of physical damage, such as chafing, melting, or corrosion on the connectors. Wiggle the harness and connectors to see if the fault is intermittent.

2. 2

   Inspect the fuse panel for any blown fuses related to the engine controls or ECU.

3. 3

   Disconnect the electrical connector at the fan clutch solenoid and check for corrosion, bent or pushed-out pins, and moisture intrusion. Ensure the connector is clean and makes a solid connection when re-seated.

4. 4

   With the connector unplugged, use a multimeter to measure the resistance across the two pins of the fan clutch solenoid (specified resistance is 2.86 to 3.3 ohms). A reading of 'OL' indicates an open circuit, while a reading significantly outside the specified range suggests a faulty coil.

5. 5

   With the key on and engine off (or running, depending on the system's logic), carefully back-probe the harness-side connector and use a multimeter to check for the correct supply voltage being sent to the solenoid from the ECU. The absence of voltage could point to a wiring issue upstream or a problem with the ECU driver circuit.

6. 6

   With the solenoid disconnected, check for continuity between the power supply wire in the harness and the chassis ground. There should be no continuity; if there is, it indicates a short circuit in the wiring.

1. 1

   Disconnect power

   Disconnect the negative battery terminal before starting any electrical repairs.

2. 2

   Repair wiring harness

   If a break or short is found during diagnostics, cut out the damaged portion and splice in a new wire of the same gauge using weatherproof heat-shrink butt connectors. Secure the harness away from sharp edges or hot components.

3. 3

   Replace viscous fan clutch assembly

   If the solenoid coil is identified as the fault, replace the viscous fan clutch assembly. Remove the fan shroud, loosen the serpentine belt, remove the cooling fan from the hub, and unbolt the clutch assembly from the engine pulley. Install the new assembly, torque to manufacturer specifications, and reinstall the fan, belt, and shroud.

4. 4

   Clear fault codes

   Reconnect the battery and use a diagnostic tool or the tractor's onboard display to clear the active fault code.

5. 5

   Verify repair

   Start the engine and bring it up to operating temperature. Monitor the fan operation to ensure it engages and disengages correctly as the engine's cooling demands change. Check for any recurring fault codes.