New Holland ENG 3285 – Engine Control Unit (ECU): EDC: Sensor Supply Voltage 3 - High

The Engine Control Unit (ECU) has detected the voltage on the 'Sensor Supply 3' circuit is above the upper acceptable limit (typically > 5.5V) or is shorted to a high voltage source (like the 12V battery).

• L220
• SR175
• T7 Series
• T8 Series
• T9 Series
• W190B
• 721F
• 821F
• 921F
• CR Series
• CR10.90

1. 1

   Verify the machine's base battery voltage is sufficient and not overcharging, which can skew ECU diagnostics.

2. 2

   Turn the key to the ON position and measure the voltage at the sensor connector pins (Supply pin to Chassis ground). It should read between 4.5V and 5.5V.

3. 3

   Disconnect the Fuel Rail Pressure Sensor and the Intake Air Humidity/Temperature Sensor one at a time. If the voltage returns to normal (or the code changes to Low/Open), the unplugged sensor has an internal short.

4. 4

   Inspect the wiring harness between the sensors and the ECU for chafed wires where the 5V supply wire might be shorting against a 12V power source.

5. 5

   If the wiring harness tests perfectly and sensors are unplugged but the ECU still outputs excessive voltage on the Supply 3 pin, test the ECU for an internal 5V regulator failure.

1. 1

   Disconnect battery

   Turn off the machine and disconnect the battery if performing harness repairs or replacing the ECU.

2. 2

   Replace faulty sensor

   If a sensor is faulty: Remove the defective Fuel Rail Pressure Sensor or Intake Air Humidity/Temperature Sensor. Install the new OEM sensor and torque to manufacturer specifications. Reconnect the wiring harness.

3. 3

   Repair wiring harness

   If the wiring is faulty: Locate the short-to-battery in the harness. Repair the damaged wire using approved OEM splicing techniques and heat-shrink tubing.

4. 4

   Replace Engine Control Unit

   If the ECU is faulty: Replace the Engine Control Unit. Note: If the EDC/ECU is replaced, you must use the appropriate CNH service tool (e.g., Electronic Service Tool / EST) to restore self-learning parameters and engine datasets.

5. 5

   Clear fault codes

   Clear the fault codes using a diagnostic tool and run the engine to verify the repair.