CLAAS Id7636h / 7636h (423) – TR2 (A57-2) / TR2 A142: Error on high pressure braking.

This fault indicates an anomaly in the high-pressure braking circuit during the machine's initialization phase. Specifically, the system detects that the hydraulic brake pressure is ranging between 78 and 98 bars during initialization, which is outside of the expected normal threshold. As a safety measure, the engine speed is severely limited to 300 rev/min.

• CLAAS Axion 800 Series (810, 850)
• CLAAS Axion 900 Series (920, 950)
• CLAAS Arion 500 / 600 Series (510, 530, 640, 650)

1. 1

   Perform an initial reset test by pumping the brake pedal for 15 seconds, then starting the tractor.

2. 2

   Check the actual physical hydraulic pressure in the circuit using a gauge and compare it with the electronic value measured by the high-pressure braking pressure sensor (B368 or B370).

3. 3

   Inspect the high-pressure braking solenoid valve (Y329) to ensure it is receiving power and opening correctly.

4. 4

   Check the wiring harnesses and connectors linking the TR2 module, the B368/B370 pressure sensors, and the Y329 solenoid for continuity, proper power supply, correct signal voltage, short-circuits, or open circuits.

5. 5

   Check for any physical hydraulic leaks on the braking circuit, paying close attention to the decompression screw and non-return valves.

6. 6

   Monitor the service brake accumulators. If the system is inflating too often or failing to reach the threshold within 10 seconds, the accumulator may be failing.

1. 1

   Prime the System

   With the tractor off, pump the brakes continuously for 15 seconds, then start the engine. If the code clears and full engine RPM is restored, the system simply lost prime or pressure during shutdown.

2. 2

   Repair Wiring

   If the code persists, use a multimeter to test the harness between the TR2 (A57-2) module and the high-pressure brake sensors/solenoids. Repair any broken wires or corroded pins.

3. 3

   Fix Hydraulic Leaks

   If physical leaks are found during the diagnostic phase, replace the faulty hydraulic lines, fittings, or non-return valves.

4. 4

   Replace Faulty Sensors/Valves

   If the B368/B370 sensor is reading incorrectly compared to actual line pressure, or if the Y329 solenoid is failing to actuate when powered, replace the defective component.

5. 5

   Replace the Accumulator

   If the system cannot hold pressure between 78 and 98 bars properly due to an internal diaphragm tear, replace the rear service brake accumulator.

6. 6

   Module Replacement (Worst Case)

   If all sensors, wiring, and hydraulics are perfect, the TR2 (A57-2) module itself may be faulty. Replacement requires reprogramming using CLAAS diagnostic tool n° 60 05 033 249.