Case IH 2401 – TCU (Tractor Control Unit): FNRP enable short to ground

The Low Side Driver (LSD) PWM duty cycle is above 20%, but the current is less than 9.8 milliamps for 100 milliseconds. This indicates a short circuit to ground in the FNRP enable circuit. Possible failure modes include a faulty connector, a faulty shuttle lever (FNRP pod), a damaged wiring harness, or a faulty Tractor Control Unit (TCU).

• Steiger T4B
• Magnum Tier 4A CVT
• Magnum Tier 4B CVT
• Magnum 235 CVT
• Magnum 260 CVT
• Magnum 290 CVT
• Magnum 310 CVT
• Magnum 315 CVT
• Magnum 340 CVT
• Magnum 380 CVT
• Steiger
• Quadtrac

1. 1

   Turn off the machine and locate the FNRP pod (shuttle lever) connector X-051

2. 2

   Disconnect the connector and use a multimeter to measure continuity between pin 4 at the FNRP connector (X-051) and a known good chassis ground

3. 3

   Verify the reading: there should be no continuity (open circuit). A reading of less than 1.0 Ω confirms a short to ground in the wiring harness

1. 1

   Harness Repair

   If the diagnostic check revealed continuity to ground (less than 1.0 Ω), trace the wiring harness from the FNRP pod to the TCU. Look for chafed wires, pinched looms, or damaged connectors. Repair or replace the damaged section of the harness as required.

2. 2

   Software Update

   If no continuity to ground is found (the harness is good), the issue may be a software glitch. Connect the electronic service tool (EST) and download the correct/latest level of software to the TCU.

3. 3

   Clear and Test

   Clear all active and stored fault codes. Cycle the key and test the FNRP shuttle lever operation in all positions (Forward, Neutral, Reverse, Park).

4. 4

   Component Replacement

   If the harness is intact, the software is updated, and the fault code returns, the failure is internal to either the FNRP Shuttle Lever Pod or the Tractor Control Unit (TCU). Replace the FNRP pod first as it is the most common physical failure point for this circuit. If the issue persists, replace the TCU.