Case IH 3754 (DTC E6DD) - ECU – Engine Control Unit (ECU / ECM): ECU internal failure - Rail pressure plausibility

Level 2 Monitoring diagnostic fault check indicating that the engine control module has detected an implausible condition in the fuel rail pressure monitoring system. The fuel pressure readings being reported to the computer do not match the expected parameters.

• MAXXUM T4E
• 240 Series Axial-Flow Combines
• 7240
• 8240
• 9240
• Farmall 90C
• Farmall 95A
• Farmall 100C
• Farmall 110U
• Farmall 115U
• Farmall 120C
• Maxxum 110
• Maxxum 115
• Magnum series

1. 1

   Check if the fuel level was too low when the failure occurred, which can cause the system to suck in air

2. 2

   Check the low-pressure fuel tubes, ensuring the return line from the common rail pump to the tank is free and not blocked

3. 3

   Check for clogged fuel filters or leaking pre-supply tubes

4. 4

   Inspect the wiring harness and connectors for the fuel rail pressure sensor for shorts, opens, or corrosion

5. 5

   Check if the fuel metering unit on the high-pressure pump is stuck in the open position

6. 6

   Check if the Pressure Relief Valve (PRV) has exceeded its maximum open count or if its opening pressure is too low

7. 7

   Check for internal high-pressure leaks at the injectors or a leaking pressure control valve

1. 1

   Resolve Fuel Supply Issues

   Fill the fuel tank and bleed the fuel system to ensure no air is trapped in the lines. Replace the primary and secondary fuel filters if they are clogged.

2. 2

   Clear Return Lines

   Disconnect and blow out the low-pressure fuel return lines to ensure there are no restrictions causing high back-pressure.

3. 3

   Test/Replace the Rail Pressure Sensor

   Using a multimeter, verify the 5V reference and signal integrity on the rail pressure sensor harness. If the wiring is good but the sensor is reading erratically or sticking, replace the fuel rail pressure sensor.

4. 4

   Address the PRV

   If diagnostic tools indicate the Pressure Relief Valve is faulty or opening prematurely, replace the PRV. Note: If the PRV is replaced, the timer monitoring its opening status must be reset using the appropriate routine control service tool.

5. 5

   Address the Metering Unit

   If the metering unit is diagnosed as stuck open, it must be cleaned or replaced.

6. 6

   ECU Recalibration/Replacement

   If all physical fuel components and wiring test perfectly, the ECU itself may have a calibration error or internal hardware failure. Contact Helpdesk for authorization to reflash or replace the ECM.