New Holland 3386 – ECU / CCM: Fan Speed Increase Circuit Open/Short

The Engine Control Module (ECM) has detected that the electrical circuit responsible for increasing the cooling fan's speed is either broken (an open circuit) or has made an unintended connection to the chassis ground (a short to ground). This condition prevents the ECM from effectively commanding the fan to speed up, which can leave the fan stuck at a low speed or completely inoperative, leading to a risk of engine overheating under load. The system may default to a fail-safe mode, attempting to run the fan at maximum speed constantly to prevent damage.

• TR88
• TR89
• TR98
• TR99
• CR920
• CR940
• CR960
• CR970
• CR9040
• CR9060
• CR9070
• CR9080
• CR9090
• CR7.90
• CR8.90
• CR9.90
• CR10.90
• CX840
• CX860
• CX880
• CX8070
• CX8080
• CX8090
• CX7.90
• CX8.80
• CX8.90
• TC5060
• TC5070
• TC5080
• TC5.80
• TC5.90
• TX66
• TX68

1. 1

   Visually inspect the wiring harness leading to the cleaning fan speed actuator motor for chafed or melted insulation, pinched wires, or corrosion (especially where it rubs against the frame).

2. 2

   Check for debris packed around the actuator and its gears, which can cause binding and potentially overload the circuit.

3. 3

   With the ignition on and separator engaged, have a helper operate the fan speed increase switch while you check for 12V power at the actuator motor connector.

4. 4

   Disconnect the battery and perform a continuity test on the signal wire between the controller and actuator to check for an open circuit (a reading of 'OL' indicates a break).

5. 5

   Perform a short-to-ground test by checking for continuity between the signal wire and a clean, unpainted point on the machine's chassis.

6. 6

   If voltage is present but the motor does not move, test the actuator motor directly by carefully applying 12V and ground from a separate power source to its terminals.

1. 1

   Safety First

   Shut off the engine, set the parking brake, and remove the key. Disconnect the battery before performing electrical repairs.

2. 2

   Locate and Access the Actuator

   The cleaning fan speed actuator is an electric motor mounted to the variable speed pulley assembly for the cleaning fan, typically on the right side of the combine. Access may require removing side shields.

3. 3

   Test the Circuit

   Perform the diagnostic checks listed in the section above to confirm whether the fault lies in the wiring or the actuator motor itself.

4. 4

   Repair Wiring

   If an open or short circuit is found, repair the damaged section of the harness or replace the faulty wire. Ensure all connections are clean, secure, and protected from future damage.

5. 5

   Replace the Actuator Motor

   If the actuator motor is confirmed to be faulty, unbolt it from its mounting bracket and disconnect the linkage to the variable pulley. Install the new motor, ensuring the gears mesh correctly and the linkage is reconnected.

6. 6

   Adjust and Verify

   After replacement, it may be necessary to perform an adjustment or calibration procedure to ensure the full range of fan speed is achievable. A general procedure involves running the fan to its maximum and minimum speeds and adjusting the limit nuts on the actuator shaft.

7. 7

   Clear Codes and Test

   Reconnect the battery, start the machine, and clear the fault codes using the in-cab monitor if possible. Operate the fan speed control to verify that the system is functioning correctly throughout its entire range.