Case IH 496 – Engine Control Module (ENG / ECM): Engine Speed / Position Sensor #2 supply is too low.

The Engine Control Module has detected that the 5-volt reference supply circuit going to the #2 engine speed/position sensor has dropped below the normal operating threshold. This is typically caused by a short circuit to ground in the supply line, a short between the supply and return lines, an internally shorted sensor pulling the voltage down, or a failed ECM power supply.

• MX Magnum
• STX Steiger
• Magnum Series
• Puma Series
• Maxxum Series
• Farmall Series
• Steiger / STX Series
• Case IH combines
• Case IH sprayers

1. 1

   Visual Inspection: Inspect the wiring harness and connectors leading to the Engine Speed / Position Sensor #2 for rubbing, chafing, melted insulation, or corrosion.

2. 2

   Voltage Test: Disconnect the sensor and turn the key to the ON position. Measure the supply voltage at the harness connector. It should read approximately +5 VDC.

3. 3

   Isolate the Sensor: If the voltage returns to a normal 5V when the sensor is unplugged, the sensor itself is internally shorted and must be replaced.

4. 4

   Harness Check: If the voltage remains low with the sensor disconnected, the fault lies in the wiring harness (a short to ground or short to the return line) or the ECM itself.

1. 1

   Disconnect Power

   Disconnect the battery ground cable before servicing engine electronics.

2. 2

   Locate the Sensor

   Locate the Engine Speed / Position Sensor #2. Depending on the engine build, this will be located either near the camshaft gear or down by the crankshaft damper/flywheel.

3. 3

   Remove the Sensor

   Unplug the wiring harness connector. Remove the retaining bolt (often requiring an 11/16" sensor socket or standard metric socket depending on the engine) and carefully pull the sensor out of the engine block.

4. 4

   Inspect the Port

   Look through the sensor mounting hole to inspect the tone wheel/reluctor for any physical damage or debris.

5. 5

   Install the New Sensor

   Lightly oil the O-ring on the new sensor. Insert it into the block—do not pinch the O-ring.

6. 6

   Torque to Spec

   Tighten the retaining bolt. (Note: For many Cummins-based Case IH engines, the torque spec is 177 in-lb / 20 N.m, but avoid over-torquing plastic-flange sensors).

7. 7

   Reconnect

   Push the harness connector onto the sensor until it clicks and locks.

8. 8

   Test

   Reconnect the battery, clear the fault codes using a diagnostic tool, and run the engine to verify synchronization and idle quality.