Case IH 12523 – ABS Control Module or Vehicle Electronic Control Unit (VECU): During normal braking, left, right, or front AoH stroke is too long.

The stroke sensor on the AoH converter is detecting excessive piston travel when the brakes are applied. This typically indicates air in the hydraulic brake lines, a hydraulic fluid leak, or severely worn brake components requiring excessive fluid displacement.

• Case IH Puma Series (170, 185, 200, 215, 230, 240, and CVX/CVT variants)
• Case IH Optum Series
• Case IH Magnum Series

1. 1

   Check hydraulic brake fluid/mineral oil level in the reservoir (low level causes excessive stroke)

2. 2

   Visually inspect the left AoH converter, hydraulic brake lines, and wheel cylinders for fluid leaks

3. 3

   Inspect brake discs/pads for severe wear, which requires the AoH piston to travel further to engage

4. 4

   Check for air trapped in the hydraulic side of the left AoH circuit, which causes inconsistent pressure and excessive stroke

5. 5

   Inspect the wiring harness and connectors at the left AoH converter's pressure and stroke/position sensors for corrosion or damage

1. 1

   Preparation

   Park the tractor on a level surface, engage the parking brake, and turn off the engine. Chock the wheels.

2. 2

   Depressurize Systems

   Pump the brake pedal several times to deplete any residual hydraulic pressure. Drain the pneumatic air tanks to remove air pressure from the system.

3. 3

   Access the Component

   Depending on the exact model and AoH location, you may need to remove the front wheels to access the front/side-mounted AoH converters. Warning: Use adequate lifting equipment for heavy components.

4. 4

   Disconnect Lines

   Disconnect the pneumatic brake valve supply hose and the hydraulic steering/brake hoses. Tip: Mark or label the position of all hoses to ensure correct reinstallation.

5. 5

   Disconnect Electricals

   Unplug the electrical connector for the AoH stroke/position sensor.

6. 6

   Remove the Converter

   Detach the pipe bracket, unbolt the AoH mounting bracket, and remove the AoH converter assembly from the tractor.

7. 7

   Installation

   Mount the new AoH converter and reconnect all hydraulic, pneumatic, and electrical lines.

8. 8

   Bleed the System

   You must thoroughly bleed the hydraulic brake circuit to remove all air. Refill with the specified brake fluid (e.g., Case IH Akcela Nexplore or LHM mineral oil, depending on your exact machine's spec).

9. 9

   Calibration

   Clear the fault codes using a diagnostic tool and perform a brake system test to ensure the stroke length and pressures are reading correctly.