Case IH F-637-02 - ECU – Engine Control Unit (ECU): Crankshaft speed sensor pattern is not plausible

The Electronic Control Unit (ECU) evaluates the signals received from the crankshaft speed sensor to determine engine angle, speed, signal plausibility, and quality. If the ECU detects an incorrect pulse pattern, electrical noise, or determines that more than eighty crankshaft signal plausibility errors have occurred, it will log this fault. When active, the ECU may initiate an engine derate, reducing engine power by 20% per minute until it reaches 50% of its nominal power to protect the engine.

• MAGNUM AFS Connect
• CVX series (140, 150, 160, 175, 195)
• Magnum series (210, 230, 255, 285)
• Farmall
• Puma
• Maxxum
• 240 Series Axial-Flow Combines
• Engines with displacements of 6.8L, 8.1L, 9.0L, and 12.5L

1. 1

   Check if the tractor battery power supply has been connected to an external power supply. If connected, disconnect it and test for normal operation to rule out signal interference.

2. 2

   Inspect the wiring harness and connectors for the crankshaft position sensor (B231) for short-circuits, open circuits, or electrical noise.

3. 3

   Check the sensor's resistance and physical adjustment/mounting to ensure it is reading the gear rim correctly.

4. 4

   Check the sources of energy (fuses, supply voltage, and ground) to the sensor.

5. 5

   Verify the engine module (ENG A15 / A-095) is functioning and check for compatibility of program versions or calibration settings.

1. 1

   Disconnect battery

   Turn off the machine and disconnect the battery to ensure safety and prevent electrical spikes.

2. 2

   Locate sensor

   Locate the crankshaft speed sensor on the engine block.

3. 3

   Inspect connector and pins

   Disconnect the electrical connector from the sensor and inspect the pins for corrosion, damage, or pushed-out terminals.

4. 4

   Repair wiring or extract sensor

   If the wiring is damaged, repair the harness. If the wiring is intact but the sensor failed the resistance/plausibility test, remove the sensor mounting bolt and extract the sensor.

5. 5

   Install new sensor

   Install the new crankshaft speed sensor and secure it.

6. 6

   Reconnect connector

   Reconnect the electrical connector.

7. 7

   Reconnect battery

   Reconnect the battery.

8. 8

   Clear fault code

   Start the engine and use a diagnostic tool to clear the stored F-637-02 / 3089 fault code.

9. 9

   Verify repair

   Run the engine to verify that the code does not return and that full engine power is restored.