Case IH 3003 (DTC 28B1) – Engine Control Module (ECM): Foot Throttle Sensor - Signal Below Range Min

The control module detects that the voltage signal returning from the foot throttle potentiometer has dropped below the minimum acceptable threshold. This is almost always caused by a severed signal wire (open circuit), a signal wire rubbing against the chassis (short to ground), or an internal failure of the throttle potentiometer itself.

• MAXXUM T4E
• VESTRUM CVX
• Magnum series
• Steiger series
• Puma series
• MX/TG series
• Farmall compact tractors
• TV370B
• TV450B

1. 1

   Visually inspect the foot throttle pedal assembly in the cab for physical damage, debris jammed under the pedal, or a disconnected harness.

2. 2

   Disconnect the 6-cavity electrical connector (X-252) at the foot throttle sensor and check for pushed-back pins, corrosion, or moisture.

3. 3

   Turn the key ON (engine off) and use a multimeter to verify that the sensor is receiving its 5-volt reference supply from the ECM and that the ground circuit has good continuity.

4. 4

   Test the signal wire from the throttle sensor connector back to the ECM for continuity and ensure there is no continuity to ground (which would confirm a short to ground).

5. 5

   Perform a sensor sweep test using a diagnostic tool (like Case IH EST or Jaltest) to monitor live voltage data. Slowly press the pedal; the voltage should rise smoothly. If it stays flat at 0V or drops out erratically, the sensor is internally faulty.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical spikes during the repair.

2. 2

   Access the Sensor

   Locate the foot throttle pedal assembly on the cab floor.

3. 3

   Disconnect Wiring

   Unplug the 6-pin Metri-Pack electrical connector from the foot throttle sensor.

4. 4

   Harness Repair

   If your diagnostic checks revealed a short to ground or broken wire in the pigtail, splice in a new connector pigtail or repair the damaged wire using heat-shrink connectors.

5. 5

   Remove the Sensor/Pedal

   If the sensor itself is faulty, remove the mounting bolts securing the foot throttle sensor bracket to the cab floor.

6. 6

   Install the New Part

   Mount the replacement foot throttle sensor/pedal assembly and tighten the hardware.

7. 7

   Reconnect

   Plug the 6-cavity electrical connector back into the new sensor. Reconnect the battery.

8. 8

   Clear Codes and Test

   Turn the key ON, clear the 3003 fault code using a diagnostic scan tool, and start the engine. Depress the foot throttle to ensure the engine RPM responds smoothly and the code does not return.