Case IH 17907 (F-3511-03) - ECU – Engine Control Unit (ECU): ECU 5 volt sensor supply 3 over voltage failure

The ECU detects that the voltage on the #3 sensor supply circuit has exceeded the maximum threshold (over voltage / out of range high). This typically indicates a short to a higher voltage source (like a 12V battery wire) or an internal ECU driver failure.

• VESTRUM CVX
• Magnum series (180, 200, 220, 240, 250, 280, 310, 340, 380)
• Steiger series (370, 420, 470, 500, 540, 580, 620)
• Puma series (130-240)
• Optum series
• Quadtrac series
• Farmall series
• Workmaster models
• Case wheel loaders (1021F, 1121F, 721F)
• crawler dozers (1150K, 1650L)
• backhoe loaders

1. 1

   Identify sensors on the 5V Supply 3 circuit (typically Engine Oil Rifle Pressure, Intake Manifold Air Temperature, and Barometric Pressure sensors)

2. 2

   Disconnect the sensors on the #3 supply circuit one at a time to isolate a potentially internally shorted sensor (if voltage returns to normal, the disconnected sensor is faulty)

3. 3

   Inspect the engine wiring harness for chafing, melting, or pinch points where the 5V wire might be rubbing against a 12V power wire

4. 4

   Disconnect the main ECU harness and check for moisture, corrosion, or bent pins that could bridge connections and cause voltage spikes

1. 1

   Power Down

   Turn the key switch to the OFF position and disconnect the battery ground to prevent electrical spikes.

2. 2

   Disconnect ECU and Sensors

   Disconnect the main engine harness from the ECU and disconnect all sensors on the 5V Supply 3 circuit.

3. 3

   Test the Harness

   Using a digital multimeter, check for continuity between the 5V supply wire and the main 12V battery supply wires. There should be no continuity (infinite resistance). If continuity exists, locate the short in the wiring harness and repair or replace the damaged section.

4. 4

   Test ECU Output

   If the harness tests good, reconnect the ECU (leave sensors disconnected), turn the key ON, and carefully measure the voltage output at the ECU pin for Sensor Supply 3. If the ECU is outputting significantly more than 5 volts with nothing attached, the ECU has an internal hardware failure.

5. 5

   Replace and Reprogram

   If the ECU is faulty, replace it with a new or remanufactured unit. Note: A replacement ECU must be flashed/programmed by a dealer with the correct engine dataset and self-learning parameters for your specific machine.

6. 6

   Clear Codes

   Reconnect all components, clear the fault codes using a diagnostic service tool, and run the engine to verify the repair.