CLAAS Id7622h / 7622h (403) – TR2 (A57-2) Transmission Module: Pressure of high-pressure brakes does not drop, or too high.

The system detects that the high-pressure braking circuit is not depressurizing as expected or has exceeded the maximum threshold. Specifically, the pressure value reported by the sensor is greater than around 2 to 4 bar of the real pressure in the circuit, or it is failing to regulate within the normal accumulator range (e.g., instead of 98 bar < pressure < 120 bar). Symptoms: The brake indicator light will be BLINKING. There is no audio warning triggered by this specific code.

• Axion 810
• Axion 850
• Axion 920
• Axion 950
• Arion 510
• Arion 620
• Arion 640

1. 1

   Inspect the service brakes hydraulic circuit (valves, pipes, switches, and selectors) for blockages, pinched lines, or mechanical seizing.

2. 2

   Check the Braking Pressure Sensor (B233 / B368) for measurement consistency. Verify if the sensor is falsely reporting a pressure 2 to 4 bar higher than the actual circuit pressure.

3. 3

   Check the High-Pressure Braking Solenoid Valve (Y329) for correct opening operation and verify its power supply.

4. 4

   Check the connectors and continuity of the harnesses linking the sensor and solenoid to the ECU. Look for short-circuits, open circuits, or poor grounds.

5. 5

   Test the 'Auto 5' transmission module using the official CLAAS diagnostic tool (Tool n° 60 05 033 249).

1. 1

   Depressurize the System

   Safely relieve the pressure in the high-pressure braking circuit using the braking system decompression screw before opening any hydraulic lines.

2. 2

   Inspect and Test the Sensor

   Locate the Braking Pressure Sensor (B233) on the conjunctor/disjunctor block. Test its voltage output against actual mechanical gauge pressure. If the sensor is skewed (reading artificially high), replace the sensor.

3. 3

   Inspect the Solenoid Valve

   Locate the High-pressure braking solenoid valve (Y329). Test the coil resistance and ensure the valve spool is not mechanically stuck closed, which would prevent pressure from dropping. Clean or replace the valve if it fails to actuate.

4. 4

   Test the Control Module

   If the hydraulics and sensors test fine, connect the CLAAS "Auto 5" input/output control harness (Tool 60 05 033 249) to verify the TR2 module is sending the correct PWM signals to the valve. Replace the Auto 5 module if it is internally shorted or failing to command the pressure drop.

5. 5

   Reinitialize and Test

   After replacing the faulty component, clear the fault code. Start the tractor and pump the brake pedals for 2 to 15 seconds to reinflate the accumulators. Verify that the brake indicator light stops blinking and the pressure regulates normally.