Case IH 3266 – Engine Control Module (ECM): Redundant Engine Speed in Overrun Monitoring - Speed Signal Not Plausible

The engine control module is receiving conflicting, erratic, or implausible RPM data from the engine's speed sensors (crankshaft and/or camshaft position sensors) during overrun monitoring.

• Farmall
• Magnum
• Steiger
• Puma
• Maxxum
• Skid Steer Loaders
• Compact Track Loaders
• Titan
• Trident NL5000G5

1. 1

   Check the wiring harness and connectors leading to both the crankshaft speed sensor and the camshaft speed sensor for damage, corrosion, short circuits to battery/ground, or open circuits.

2. 2

   Verify the battery and ECU voltage supply, as excessive or insufficient voltage can cause sensor plausibility errors.

3. 3

   Ensure the sensors are mounted correctly and that the gap between the sensor tip and the flywheel/gear teeth is within factory specifications (typically 0.5-2mm).

4. 4

   For certain engines (like the F5C), attempt to reload the Engine Dataset to see if a software glitch is causing the plausibility error.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent electrical shorts during repair.

2. 2

   Locate the Sensors

   Locate the crankshaft speed sensor (typically mounted on the side of the engine block near the flywheel) and the camshaft speed sensor (located near the camshaft gear/timing cover).

3. 3

   Remove the Faulty Sensor

   Disconnect the electrical pigtail from the sensor. Remove the retaining bolt(s) and carefully pull the sensor out of the engine block.

4. 4

   Clean and Install

   Clean the mounting surface thoroughly to ensure the new sensor sits flush. Install the new sensor (no modifications are usually needed as they are magnetic pickups) and tighten the retaining bolt to spec.

5. 5

   Reconnect and Test

   Reconnect the wiring harness. Reconnect the battery, start the engine, and use a diagnostic tool to clear the 3266 fault code.

6. 6

   ECU Replacement (If Necessary)

   If the failure persists after sensor replacement, wiring checks, and reloading the engine dataset, replace ECU (internal defect).