CLAAS Id7620h / 7620h (401) – TR2 (A57-2) Transmission Module: Pressure of high-pressure brakes < 70 bar at initialisation.

When the tractor is started (initialisation phase), the system expects the high-pressure braking circuit to reach a minimum standby pressure (typically between 77 and 92.9 bar in the accumulators). This code triggers if the pressure in the high-pressure brake circuit fails to reach 70 bar. This condition will trigger an audio warning and cause the brake indicator light to remain steadily "on".

• Axion 810
• Axion 850
• Axion 920
• Axion 950
• Arion 510-550
• Arion 610-650

1. 1

   Inspect the service brakes hydraulic circuit for physical leaks, damaged pipes, or selector valve issues

2. 2

   Check the braking pressure sensor (B233 or B368) for measurement consistency and ensure it is not disconnected

3. 3

   Verify that the high-pressure braking solenoid valve (Y329) is opening correctly and receiving proper power supply

4. 4

   Check the rear service brake pressure accumulator (5063 or 5016) to ensure it is not torn, faulty, or inflating too frequently

5. 5

   Inspect wiring harnesses and connectors for the sensor, valve, and accumulator for continuity, power supply, and signal integrity

6. 6

   Check the voltage delivered by the transformer (V24)

1. 1

   Visual & Leak Inspection

   Start by visually inspecting the entire high-pressure braking hydraulic circuit. Repair any leaking lines or fittings.

2. 2

   Test Electrical Connections

   Disconnect the harnesses at the Y329 solenoid valve and the B233/B368 pressure sensor. Use a multimeter to verify continuity and check for short circuits to the ground or 12V.

3. 3

   Test the Solenoid Valve (Y329)

   Command the valve using the diagnostic tool or supply test voltage to ensure it clicks and opens mechanically. If it fails to actuate, replace the Y329 solenoid valve.

4. 4

   Test the Pressure Sensor (B233/B368)

   Compare the live pressure readings on the CLAAS Diagnostic System (CDS) against a manual pressure gauge hooked up to the braking pressure tap (9022). If the sensor reading is erratic or dead, replace the sensor.

5. 5

   Inspect the Accumulator

   If the sensor and valve are functioning but pressure won't build, the conjunctor/disjunctor block or the brake accumulators (5016/5063) may have failed internally (e.g., ruptured diaphragm). Depressurize the system using the braking system decompression screw (6062) before removing and replacing the accumulator.

6. 6

   Module Verification

   If all physical components and wiring are intact, the TR2 (A57-2) module itself may be faulty. CLAAS documentation notes to test the "Auto 5" module using diagnostic tool n° 60 05 033 249, and change the module if required.

7. 7

   Clear Codes and Reinitialize

   After repair, restart the vehicle. Depress the brake pedals to inflate the brake accumulators. The error code will disappear automatically when the pressure in the rear brake circuit rises above the accumulator inflation start threshold during the reinflation phase.