CLAAS Id7637h / 7637h (424) – TR2 (A57-2): Error on high pressure braking

The high-pressure brake accumulator inflates too often, indicating a risk of leaks in the energy reserve or rear brake circuit. The system flags this error when the high-pressure braking circuit is reinflated too frequently (e.g., 4 times over a period of 40 minutes, or twice in less than 10 minutes) without any action being taken on the brake pedals.

• Axion 800
• Axion 810
• Axion 850
• Axion 900
• Axion 920
• Axion 950
• Axion 960
• Arion 510
• Arion 530
• Arion 550
• Arion 620
• Arion 640
• Arion 650

1. 1

   Check the entire service brakes hydraulic circuit for physical leaks (valves, pipes, selectors, etc.)

2. 2

   Ensure there is no air trapped in the braking circuit

3. 3

   Check the left-hand brake pedal switch (Z126) and right-hand brake pedal switch (Z127) for signal consistency, correct switch settings, and proper brake pedal upper stop positioning

4. 4

   Check the high-pressure braking pressure sensor 1 (B368) on the rear brake circuit for measurement consistency against actual physical pressure

5. 5

   Check the high-pressure braking solenoid valve (Y329) to ensure it is opening correctly and receiving proper power supply

6. 6

   Inspect the rear service brake pressure accumulator (5063) to see if the internal diaphragm is faulty or torn

7. 7

   Check the wiring harnesses and connectors for all aforementioned components for continuity, power supply, and signal integrity

1. 1

   Initial Reset

   Cancel the fault code via the diagnostic terminal. Restart the tractor. If the error does not reappear, it may have been a transient pressure drop.

2. 2

   Bleed the Brakes

   If the error persists, bleed the brake hydraulic circuit to eliminate air as a potential cause of frequent reinflation.

3. 3

   Address Leaks

   Trace the rear brake circuit lines. Tighten any loose fittings or replace leaking hydraulic pipes/selectors.

4. 4

   Test/Replace Switches and Sensors

   If no physical leaks are found, use a multimeter or the CLAAS Diagnostic System (CDS) to verify the operation of the Z126/Z127 pedal switches and the B368 pressure sensor. Replace if readings are out of specification.

5. 5

   Replace the Accumulator

   If the system is constantly losing pressure internally without external leaks, the nitrogen charge in the accumulator has likely failed (torn diaphragm). Depressurize the hydraulic system safely and replace the rear service brake pressure accumulator.

6. 6

   Final Verification

   After repair, restart the vehicle and carry out a test drive. The error code should disappear once the pressure in the rear brake circuit remains stable above the accumulator inflation start threshold.