Case IH F-636-09 - ECU – Engine Control Unit (ECU): Camshaft speed sensor values are not plausible

The Engine Control Unit (ECU) evaluates signals from both the camshaft and crankshaft speed sensors to determine engine angle, speed, signal plausibility, and quality. If the ECU determines that the camshaft speed signal shows no electrical errors, but no camshaft edge signal has been detected for at least four revolutions, this fault is triggered.

• MAGNUM AFS Connect
• Magnum series (180, 200, 225, 240, 250, 280, 310, 340, 380)
• Maxxum series (110, 115, 120, 125, 130, 135)
• Puma series
• Steiger series
• Farmall (40, 45, 50)
• Optum
• 240 Series Axial-Flow Combines
• Farmlift telescopic handlers

1. 1

   Check for related active faults (e.g., 3177, 3089, or 3088). If present, diagnose and resolve those first.

2. 2

   Verify that the tractor battery has not been connected to an external power supply (like a jump box or charger), as voltage irregularities can trigger plausible value faults.

3. 3

   Inspect the wiring loom for the camshaft speed sensor for rubbing, chafing, shorts, or broken wires (especially common on T4A Magnums).

4. 4

   Perform a sensor swap test by swapping the camshaft and crankshaft sensors (they are identical) to determine if the sensor itself has failed or if the issue is in the wiring/ECU.

1. 1

   Locate the Sensor

   The camshaft speed sensor is typically located on the engine timing gear housing.

2. 2

   Disconnect Battery

   Always disconnect the battery before servicing engine electrical components to prevent shorts.

3. 3

   Remove the Sensor

   Disconnect the electrical connector from the sensor. Remove the retaining bolt and carefully pull the sensor out of the housing.

4. 4

   Install the New Sensor

   Insert the replacement sensor into the housing and secure it with the retaining bolt. Reconnect the electrical harness.

5. 5

   Clear Codes and Test

   Reconnect the battery, clear the fault codes using an Electronic Service Tool, and crank the engine. Note: The engine may be hard to start initially if it is running exclusively off the camshaft speed sensor, as the ECU requires a few revolutions of the camshaft to synchronize and start the engine.

6. 6

   Advanced Timing (If Applicable)

   If the camshaft itself was replaced or the engine was rebuilt (e.g., Cursor 9L engine), a specific timing procedure must be followed using the single and double marks etched into the flywheel (Marks A, B, C, D) and pinning the flywheel through the crankshaft sensor hole.