Case IH 3090 (DTC 4212) - ECU – Engine Control Unit (ECU): Camshaft speed sensor values are not plausible

The ECU determines that the camshaft speed signal shows no inherent errors, but no camshaft edge signal has been detected at least four times. This indicates a loss of phase synchronization or an out-of-range signal.

• MAXXUM T4E
• 240 Series Axial-Flow Combines
• Puma
• Magnum Series (235-340, 315)
• STX Steiger Series (350-600 HP)
• Farmall Series (Tier 4A)
• Case 580 Super N Backhoes
• 621/721/821/921 F-Series Loaders

1. 1

   Check for External Power: Verify that the tractor battery power supply has not been connected to an external power supply. If an external power supply is connected, disconnect it and test the system for normal operation.

2. 2

   Visual Inspection: Visually inspect the relevant harnesses and connectors for damage, bent or dislocated pins, corroded terminals, or broken wires.

3. 3

   Harness Flex Test: Verify that the connectors are fully seated. Flex the involved harnesses to reveal any intermittent breaks or shorts in the wiring while monitoring the display.

4. 4

   Evaluate Raw Signals: Use a diagnostic scan tool to evaluate the raw signals and check the proper functioning and installation of the camshaft phase sensor.

5. 5

   Software Check: Check the ECU (A-095) for the appropriate software version and re-flash if necessary.

1. 1

   Disconnect External Power

   Ensure no external power sources are connected to the machine.

2. 2

   Test Continuity

   Test the wiring harness for continuity between the camshaft speed sensor and the ECU.

3. 3

   Repair Wiring

   If there is no continuity, utilize the machine's specific service manual wiring schematic to locate and repair the shorted or broken conductor. (Note: For certain models like the Magnum 315, Case IH released an updated version of the engine harness to resolve recurring 3090/3091 codes caused by wiring defects).

4. 4

   Replace Sensor

   If the wiring, connectors, and continuity are all intact but the raw signal is still missing or implausible, remove and replace the camshaft speed sensor.

5. 5

   Clear Codes

   Clear the fault codes from the ECU and run the engine to verify the repair.