Case IH 3266 – Engine Controller (EDC / ECU / ECM): Engine Overspeed Error / Plausibility Error in the Engine Speed Check

The engine control system is receiving an erratic, implausible, or missing speed signal from either the crankshaft speed sensor or the camshaft speed sensor, leading the system to incorrectly read an overspeed condition during overrun monitoring.

• skid steer
• Magnum 235–340 (Series 4)
• Steiger (350 to 600 HP)
• Puma (200, 230)
• Maxxum (110-140 EP, 110-130 EP CVX)
• Farmall (85C, 115C, 85-115A Tier 4A, 95U-105U Pro)
• Case 580 Super N Backhoes
• 621E Tier 3 Wheel Loaders
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)

1. 1

   Verify battery and supply voltage to the EDC, as excessive or insufficient voltage can cause plausibility errors.

2. 2

   Inspect the wiring harnesses for both the Crankshaft Speed Sensor and the Camshaft Speed Sensor. Look for defective wiring, short circuits to ground/battery, or reverse-connected pins.

3. 3

   Check for secondary codes (e.g., 3278, 3279) which indicate an internal EDC power defect rather than a sensor failure.

1. 1

   Access the Sensors

   Locate the Crankshaft Speed Sensor and Camshaft Speed Sensor on the engine block/bell housing.

2. 2

   Replace the Faulty Sensor

   If the wiring is intact but the speed signal remains implausible, replace the Crankshaft and/or Camshaft Speed Sensor.

3. 3

   Test the System

   Clear the codes and run the machine to monitor engine speed parameters.

4. 4

   Replace the Engine Controller

   If failure persists after reinstallation or sensor replacement, replace the ECU. An internal defect in the EDC can cause a permanent plausibility error.

5. 5

   Restore Parameters

   If the Engine Controller (EDC) is replaced, you must use the appropriate electronic service tool (EST) to 'Reload Engine Dataset' and perform the 'Procedure To Restore Self Learning Parameters'.