New Holland ENG 3280 – Engine Control Unit (ECU) / EDC7: Sensor Supply Voltage 1 - High

This fault indicates that the 5-volt reference circuit #1, which supplies power to a specific group of engine sensors, is reading a voltage higher than normal (typically shorted to a 12V power source).

• T5 Series
• T6 Series
• T7 Series
• T8 Series
• T9 Series
• CR Series
• CX Series
• CR9090
• CX8080
• CX8090
• FR Forage Harvesters
• Magnum (235-340 Series 4)
• Puma
• Steiger

1. 1

   Check Battery Voltage: Ensure the machine's base battery voltage is correct and the alternator is not overcharging.

2. 2

   Sensor Isolation Test: Disconnect the Oil Pressure, Boost Pressure, and Fuel Low Pressure sensors one at a time to check for an internal short pulling the voltage high.

3. 3

   Harness Inspection: Check the engine wiring harness for chafing, rubbing, or melted insulation, particularly where the harness routes near the engine block, which could cause the 5V wire to short against a 12V power wire.

1. 1

   Monitor circuit voltage

   Turn off the machine and connect the CNH Electronic Service Tool (EST) or an approved diagnostic scanner to monitor the voltage on Sensor Supply Circuit 1.

2. 2

   Locate sensors

   Locate the three sensors on the engine block (Oil Pressure, Boost Pressure, Fuel Low Pressure).

3. 3

   Unplug sensors

   Unplug the sensors one by one. Monitor the live data.

4. 4

   Replace shorted sensor

   If the voltage normalizes: Replace the sensor that you just unplugged, as it has failed internally and is shorting the circuit.

5. 5

   Test 5V reference wire

   If the voltage remains high with all sensors unplugged: Use a digital multimeter to test the 5V reference wire in the harness for a short to battery voltage (12V).

6. 6

   Trace and repair harness

   Trace the harness back to the EDC. Repair or replace the wiring harness if a short to power is found.

7. 7

   Replace Engine Control Unit (EDC)

   If the wiring harness tests perfectly fine: The Engine Control Unit (EDC) has suffered an internal hardware failure on the 5V driver and must be replaced.

8. 8

   Clear fault code

   Reconnect all components, turn the key on, and use the diagnostic tool to clear the fault code.