Case IH 3089 (DTC 4412) - ECU – A-095 ECU: Crankshaft speed sensor pattern is not plausible.

This fault occurs when the Electronic Control Unit (ECU) evaluates the signals received from the camshaft and crankshaft speed sensors (checking angle, speed determination, signal plausibility, and quality) and determines that more than eighty crankshaft signal plausibility errors have occurred.

• MAXXUM T4E
• 240 Series Axial-Flow Combines
• Puma series
• Magnum series (MX210, MX230, MX255, MX285)
• Farmall series (40, 45, 50, 85C, 95, etc.)
• Maxxum series
• JX series

1. 1

   Check if the tractor's battery power supply has been connected to an external power supply (e.g., a jump box or charger). If an external power supply is connected, disconnect it and test the system for normal operation.

2. 2

   Check the battery voltage on the instrument cluster. Start the engine and run it at 2000 rev/min to ensure the charging system is providing stable voltage to the ECU.

3. 3

   Visually inspect the relevant harnesses and connectors leading to the crankshaft speed sensor and the A-095 ECU. Look for damage, bent or dislocated pins, corroded terminals, or broken wires. Verify that all connectors are fully seated and locked.

1. 1

   Resolve Wiring Issues

   If any damage was found during the visual inspection of the harness or connectors, repair or replace the affected wiring.

2. 2

   Test Operation

   Clear the codes and run the machine. If the fault has been resolved, return the machine to service.

3. 3

   Software Verification

   If the fault has not been resolved, check the A-095 ECU for the appropriate software version. Re-flash or update the ECU software if necessary, as outdated logic can sometimes cause false plausibility errors.

4. 4

   Sensor Replacement

   If the wiring is intact, voltage is stable, and the ECU software is up to date, the crankshaft speed sensor itself has likely failed internally or has a damaged magnetic pickup. Replace the crankshaft speed sensor.

5. 5

   Clear and Verify

   After replacing the sensor, clear the fault codes and run the engine to verify that the crankshaft speed sensor pattern is now reading as plausible.