Case IH 3749 (F-91-31) - ECU – Engine ECU: ECU internal failure - Accelerator pedal position sensor

The engine control module has detected an internal processing error, plausibility error, or circuitry failure specifically related to the signal coming from the accelerator pedal position sensor.

• VESTRUM CVX
• 240 Series Axial-Flow Combines
• 7240
• 8240
• 9240

1. 1

   Inspect Wiring & Connectors: Check the wiring harness between the accelerator pedal position sensor and the Engine ECU. Look for chafed wires, short circuits to ground or power, and open circuits.

2. 2

   Check Connections: Disconnect the connectors at both the pedal and the ECU. Inspect for bent pins, moisture, or corrosion.

3. 3

   Test the Sensor: Verify the sensor's supply voltage and ground. Use a multimeter or diagnostic service tool to monitor the pedal position sensor's output signal. The voltage should sweep smoothly without dropping out as the pedal is depressed.

4. 4

   ECU Verification: If the wiring harness tests perfectly and the pedal sensor is outputting the correct, stable voltage, the fault is isolated to the Engine ECU's internal hardware or software.

1. 1

   Power Down

   Turn off the machine and disconnect the battery before servicing ECU connections.

2. 2

   Resolve External Faults

   If diagnostic checks reveal damaged wiring or a faulty connector, repair or replace the affected harness section.

3. 3

   Replace Sensor

   If the accelerator pedal sensor fails the sweep test or has an internal short, unbolt the pedal assembly, disconnect the harness, and install a new accelerator pedal position sensor.

4. 4

   Address the ECU

   If the sensor and wiring are 100% functional, the Engine ECU is the culprit.

5. 5

   Reprogram/Replace ECU

   Have a certified Case IH technician either flash/update the ECU software (if a patch is available for false flags) or replace the Engine ECU entirely.

6. 6

   Clear Codes and Calibrate

   After repairs, reconnect the battery, use a diagnostic tool to clear the fault codes, and perform any required pedal calibration procedures.