Case IH 91-04 - VCM – Vehicle Control Module (VCM) or Engine Control Module (ECM): Throttle Position Sensor 1 / Accelerator Pedal Position Sensor voltage below normal

The control module is receiving an abnormally low voltage signal from the foot pedal sensor, which typically indicates a short circuit to ground, an open circuit in the wiring, or a complete internal failure of the sensor's potentiometer.

• MAGNUM AFS Connect
• Puma
• Magnum
• Steiger
• Farmall
• CVX series
• compact track loaders
• wheel loaders
• backhoes

1. 1

   Check the mechanical travel adjustment of the foot pedal. Ensure the sensor is not physically loose, misaligned, or obstructed by debris in the cab.

2. 2

   Inspect the wiring harness from the pedal to the VCM for chafing, pinched wires, or melted insulation that could cause a short to ground.

3. 3

   Disconnect the pedal sensor and check the connector for water intrusion, bent pins, or corrosion.

4. 4

   Turn the key to the ON position (engine off) and verify that the sensor is receiving the correct 5V reference power supply and has a solid ground.

5. 5

   Using a multimeter or a diagnostic tool, monitor the signal voltage while slowly pressing the pedal. The voltage should rise smoothly; if it drops to 0V or stays flat, the sensor is defective.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Access the Pedal

   Locate the accelerator pedal assembly on the floorboard of the cab. Remove any trim panels or floor mats obstructing the mounting bolts.

3. 3

   Disconnect

   Unplug the electrical harness connector from the foot pedal position sensor.

4. 4

   Remove the Assembly

   Unbolt the accelerator pedal assembly from the floorboard (on many Case IH models, the sensor is integrated into the pedal assembly and replaced as a single unit).

5. 5

   Install the New Part

   Mount the new pedal assembly or sensor and torque the mounting bolts to OEM specifications.

6. 6

   Reconnect

   Plug the electrical harness back into the sensor, ensuring the locking tab clicks into place. Reconnect the battery.

7. 7

   Calibrate and Clear

   Connect a diagnostic service tool to clear the 91-04 (SPN 91 FMI 4) fault code. Depending on the specific machine model, you may need to run a routine to calibrate the minimum and maximum travel limits of the new pedal.