Case IH 2185 – Engine Control Module (ECM) / Engine ECU: Throttle Sensor Supply Voltage High

The Engine Control Module (ECM) is detecting an excessively high voltage on the 5-volt reference circuit that supplies power to the accelerator pedal position sensor (throttle sensor). This usually means the 5V supply wire is shorted to a higher voltage source (like a 12V battery line), or the sensor itself has failed internally and is bridging circuits.

• Steiger T4B
• Magnum
• Puma (e.g., 150/175 CVT Tier 4B)
• Steiger
• Maxxum

1. 1

   Visual Inspection: Inspect the wiring harness leading to the accelerator pedal position sensor for chafing, melting, or pinch points that could cause a short to battery voltage.

2. 2

   Connector Check: Disconnect the throttle sensor and inspect the pins for corrosion, moisture intrusion, or bent terminals.

3. 3

   Voltage Test: Turn the key to the ON position (engine off). Use a multimeter to probe the sensor supply pin (Circuit 4) at the harness connector. It should read a steady 5 volts. If it reads significantly higher (e.g., 12 volts), there is a short to power in the wiring harness.

4. 4

   Resistance/Continuity Test: Check the ground circuit for the sensor to ensure it is not open, which can sometimes cause the ECM to read a floating high voltage.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to protect the ECM from voltage spikes during repair.

2. 2

   Isolate the Fault

   If the voltage test above showed 12V on the 5V line, trace the wiring harness back to the ECM, locate the short, and splice/repair the damaged wire using heat-shrink connectors.

3. 3

   Replace the Sensor (If Wiring is Good)

   If the wiring harness tests perfectly (delivering exactly 5V) but the code persists when the sensor is plugged in, the sensor has an internal short.

4. 4

   Remove the Pedal/Sensor

   Unbolt the accelerator pedal assembly or the attached throttle position sensor from the cab floorboard/console.

5. 5

   Install the New Part

   Mount the new sensor/pedal assembly and plug in the electrical connector, ensuring it clicks securely into place.

6. 6

   Clear Codes and Calibrate

   Reconnect the battery. Use a diagnostic scan tool to clear the active CA2185 fault code. Some models may require a quick throttle pedal calibration via the tractor's display monitor or scan tool so the ECM learns the new zero and 100% throttle positions.

7. 7

   Test

   Start the tractor and verify smooth throttle response without the code returning.