Case IH 18261 (518595.03, 518595.04) - ACML – ACML: Front Hitch Position Potentiometer Error State

The control module is receiving an out-of-range electrical signal from the sensor that monitors the physical height/position of the front 3-point hitch. .03 denotes signal voltage above normal (short to high voltage). .04 denotes signal voltage below normal (short to ground or open circuit). This prevents the electronic draft control and hitch management systems from operating the front hitch safely.

• MAXXUM T4E
• VESTRUM CVX
• Case IH Puma series
• Case IH Maxxum series
• Case IH Magnum series
• Case IH Vestrum and Optum series
• Case IH Steiger series

1. 1

   Mechanical Linkage Check: Visually inspect the front hitch position potentiometer. Ensure the sensor shaft has not vibrated loose from the hitch linkage lever.

2. 2

   Wiring and Connector Inspection: Check the wiring harness between the potentiometer and the ACML for physical damage, chafing, or pinched wires. Inspect the sensor connector for corrosion or pushed-out pins.

3. 3

   Voltage Test: Using a multimeter, verify that the sensor is receiving the correct reference voltage (typically 5V or 8V, depending on the specific model year) and has a solid ground.

4. 4

   Signal Test: Check the signal wire for continuity back to the ACML to rule out an open circuit.

5. 5

   Calibration Check: Verify if the system has simply lost its calibration parameters (often accompanied by related codes like 9006: "Front hitch position potentiometer – not calibrated").

1. 1

   Preparation

   Park the tractor on a level surface. Lower the front hitch completely to the ground to relieve all hydraulic pressure. Turn off the engine and remove the key.

2. 2

   Removal

   Locate the front hitch position potentiometer on the front hitch assembly. Disconnect the electrical connector.

3. 3

   Dismounting

   Remove the retaining bolts/hardware and carefully detach the sensor from the mechanical linkage lever.

4. 4

   Installation

   Install the new potentiometer. Ensure the mechanical linkage is properly aligned and securely tightened onto the sensor shaft so it moves in tandem with the hitch.

5. 5

   Reconnection

   Reconnect the electrical harness, ensuring the weather-pack seal clicks into place.

6. 6

   Calibration

   Turn the ignition key to the ON position (engine off). Access the tractor's diagnostic/calibration menu via the AFS Pro display monitor. You MUST perform the front hitch calibration procedure so the ACML can learn the new sensor's minimum (lowered) and maximum (raised) voltage limits.

7. 7

   Testing

   Clear the stored fault codes in the ACML and test the front hitch through its full range of motion to verify the repair.