Case IH 3749 (DTC E5B1) - ECU – Engine Control Unit (ECU / ECM): ECU internal failure - Accelerator pedal position sensor

This code indicates a rationality failure or internal calibration error regarding the accelerator pedal position sensor (throttle potentiometer). The Engine Control Unit (ECU) is receiving erratic, out-of-range, or implausible voltage signals from the pedal sensor, or the ECU has suffered an internal processing/calibration fault regarding the injection quantity correction based on pedal input.

• MAXXUM T4E
• Case IH 240 Series Axial-Flow® Combines (e.g., 7240, 8240, 9240)
• Case IH Tractors (Magnum, Steiger, Puma, and Maxxum series)

1. 1

   Verify the 5-volt sensor network supply voltage at the pedal connector to rule out low system voltage or a dip in the 5V reference.

2. 2

   Inspect the accelerator pedal position sensor connector for moisture, dirt buildup, or corrosion that could interrupt voltage flow.

3. 3

   Perform full continuity and resistance testing on the wiring harness between the pedal sensor and the ECU, paying special attention to the ground wire.

4. 4

   Perform a potentiometer sweep test using a multimeter or oscilloscope by slowly depressing the pedal to ensure the voltage/resistance sweep is smooth and linear without dropouts or spikes.

1. 1

   Disconnect Power

   Disconnect the machine's battery to protect the ECU and prevent short circuits during repair.

2. 2

   Clean and Repair Wiring

   If corrosion or a broken ground was found during diagnostics, clean the connector pins with electronic contact cleaner and repair any damaged wire segments.

3. 3

   Replace the Sensor

   If the wiring is intact but the sensor failed the sweep test (or if the code persists after wiring repair), remove the mounting hardware securing the accelerator pedal position sensor and install the replacement unit.

4. 4

   Reconnect Power

   Reconnect the battery.

5. 5

   Perform Calibration Cycle

   You must perform a calibration cycle for the new pedal sensor via the in-cab display monitor or by using the Case IH Electronic Service Tool (EST). Failure to calibrate the new potentiometer will result in false errors and the code returning.

6. 6

   Clear Codes and Test

   Clear the stored 3749 / E5B1 fault codes from the ECU memory. Start the engine and verify smooth throttle response across the entire RPM range.