Case IH F-637-09 - ECU – ECU: Crankshaft Speed Sensor Implausible

The Electronic Control Unit (ECU) evaluates the signals received from both the camshaft and crankshaft speed sensors to determine engine angle, speed, signal plausibility, and quality. If the ECU tests the camshaft speed sensor signal and determines it is plausible, but the crankshaft speed signal is not detected for at least two camshaft revolutions (or the signal pattern is erratic/implausible), this fault is recorded.

• MAGNUM AFS Connect
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Puma Series (165, 180, 195, 210, 225 CVX)
• Magnum Series
• Steiger Series
• Maxxum Series (100, 110, 115, 120, 125, 130, 140, 150)
• Farmall Series (85C, 115U)
• JX Series (JX90, JX95)
• Case N-Series Loader Backhoes

1. 1

   Verify Active Status: Use the Electronic Service Tool (EST) to check if the fault is currently active. If inactive, it may have been triggered by an intermittent operating condition such as engine overspeed.

2. 2

   Check for Related Faults: Look for accompanying codes (3093, 3091, 3089, 3177) that point to a broader synchronization issue.

3. 3

   Inspect Wiring & Connections: Check the wiring harness and connectors for the crankshaft speed sensor (B-019) for breaks, shorts to ground, or loose connections.

4. 4

   Check Sensor Installation: Ensure the sensor is not loose and that the gap between the sensor tip and the flywheel teeth is within specification (usually 0.5-2mm).

5. 5

   Evaluate Raw Signals: Use an oscilloscope or the EST to evaluate the raw signals of the crankshaft sensor to confirm if the sensor has lost synchronization or is completely dead.

1. 1

   Safety First

   Turn off the engine, remove the key, and disconnect the battery to prevent accidental shorts or engine cranking.

2. 2

   Locate the Sensor

   Find the crankshaft speed sensor, which typically mounts on the side of the engine block near the flywheel housing.

3. 3

   Disconnect Wiring

   Carefully unplug the electrical connector from the sensor. Inspect the harness pins for corrosion, moisture, or damage.

4. 4

   Remove the Sensor

   Remove the mounting bolt(s) securing the sensor to the engine block and pull the old sensor out.

5. 5

   Clean the Port

   Clean the mounting surface and the hole on the engine block to ensure the new sensor seats perfectly flat.

6. 6

   Install the New Sensor

   Insert the new crankshaft speed sensor. Ensure the air gap between the magnetic pickup tip and the flywheel teeth is correct (typically 0.5mm to 2.0mm).

7. 7

   Secure and Reconnect

   Tighten the mounting bolt(s) to spec and plug the electrical connector back in.

8. 8

   Clear Codes

   Reconnect the battery, start the engine, and use the EST to clear the fault codes. Run the engine to verify that F-637-09 does not return.