Case IH F-636-31 - ECU – Engine Control Unit (ECU): Compared camshaft and crankshaft speed sensor values are not plausible

The Engine Control Unit (ECU) has detected an abnormal timing pattern or offset between the crankshaft position sensor signal and the camshaft position sensor signal, indicating incorrect mechanical timing, malpositioned signal wheels, or out-of-sync signals.

• MAGNUM AFS Connect
• Magnum series (180-240)
• Puma series
• Maxxum series
• Farmall series (85C, 95C, 105U, etc.)
• Axial-Flow series (5130, 240 series)
• Case 580 Super N backhoes
• SR/SV series skid steers
• Loaders

1. 1

   Check if both the camshaft and crankshaft sensors are fixed correctly and not movable

2. 2

   Inspect the wiring harness and connectors for both sensors for intermittent open circuits, shorts to ground, or shorts to battery voltage

3. 3

   Use a diagnostic service tool to evaluate the raw signals of both the camshaft and crankshaft sensors while cranking/running

4. 4

   Check for high vibration at the crankshaft signal sensor, which can distort the reading

5. 5

   Check the correct positions of the camshaft signal wheel and crankshaft signal wheel relative to the piston position to verify neither is malpositioned or damaged

1. 1

   Inspect and Clean

   Disconnect the wiring harness from both the camshaft and crankshaft position sensors. Clean the sensor mounting areas of any dirt, oil, or debris, as magnetic pickups can be fouled by metallic debris.

2. 2

   Repair Wiring

   If the wiring harness or connectors show signs of chafing, corrosion, or damage, repair or replace the affected harness section.

3. 3

   Replace Faulty Sensor(s)

   If the diagnostic tool shows a dropped or erratic raw signal from one of the sensors, remove the mounting bolt, pull the faulty sensor, and install a direct OEM replacement.

4. 4

   Verify Mechanical Timing

   If both sensors and wiring are confirmed good but the code persists, you must physically check the engine's mechanical timing. Inspect the camshaft and crankshaft timing marks and the integrity of the signal wheels (tone rings). Adjust or replace the signal wheels if they have slipped or are damaged.

5. 5

   Clear Codes and Test

   Once repairs are made, clear the ECU fault codes using your diagnostic tool and test run the machine under load to ensure the timing offset code does not return.