Case IH 12528 – ABS Electronic Control Unit (ECU) or Vehicle Electronic Control Unit (VECU): Right AoH hydraulic pressure greater than 0.6 bar while not braking.

The system's pressure sensor is detecting residual hydraulic pressure (greater than 0.6 bar) in the right-side brake circuit even when the operator has completely released the brake pedal. This condition typically points to a dragging brake, a stuck internal valve within the right AoH converter, a blocked return line, or a faulty/drifting pressure sensor.

• Case IH Puma Series
• Case IH Puma 170
• Case IH Puma 185
• Case IH Puma 200
• Case IH Puma 215
• Case IH Puma 220
• Case IH Puma 230
• Case IH Puma CVX
• Case IH Optum Series
• Case IH Magnum Series

1. 1

   Verify the right brake pedal switch and end-of-stroke switches using a diagnostic tool to ensure the ECU is correctly receiving the 'pedal released' signal.

2. 2

   Monitor live data for the right AoH hydraulic pressure sensor. If it reads >0.6 bar, physically crack the bleeder valve on the right brake line. If fluid squirts out and pressure drops to 0 bar, there is a mechanical blockage or stuck valve. If no fluid comes out and pressure stays >0.6 bar, the sensor or wiring is faulty.

3. 3

   Disconnect the right AoH pressure sensor and check the connector for corrosion. Verify the 5V reference, ground, and signal return wires for shorts to voltage or ground.

4. 4

   Ensure the air processing unit and ABS pneumatic valves are fully exhausting air when the pedal is released.

1. 1

   Depressurize the System

   Park the tractor on a level surface, chock the wheels, and pump the brake pedals to relieve all residual hydraulic pressure. Drain the pneumatic air tanks completely.

2. 2

   Access the AoH Converter

   Depending on the tractor model and the specific location of the right AoH converter, you may need to remove the front wheels to gain safe access to the converter assembly (use lifting equipment with adequate capacity).

3. 3

   Replace the Sensor (If Faulty)

   If diagnostics proved the sensor was drifting, unthread the right AoH pressure sensor, install the new sensor, and torque to OEM specifications.

4. 4

   Replace the AoH Converter (If Mechanically Stuck)

   If the converter is holding pressure, disconnect the pneumatic lines and hydraulic lines from the right AoH converter. Cap all lines immediately to prevent contamination. Unbolt the converter from the chassis and install the replacement unit.

5. 5

   Bleed the Brakes

   Reconnect all lines. Refill the hydraulic reservoir with the specified mineral oil (e.g., CASE IH Akcela/Hy-Tran). Perform a full brake bleed procedure on the right circuit to remove all air.

6. 6

   Clear Codes

   Reinstall the wheels (if removed), power on the tractor, and use the diagnostic tool to clear fault code 12528. Test drive to ensure the brakes apply and release smoothly without dragging.