Fendt 0A.1.EC – Central electrical/hydraulic control system: Trailer brake release solenoid valve fault

Solenoid valve faulty or ABV: bypass output 2 faulty (handbrake) / bypass output 2 high fault. This indicates an electrical failure (such as a short circuit, open circuit, or excessive current draw) preventing the solenoid from properly actuating the hydraulic trailer brake valve when the handbrake is released.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• 200 V/F/P Vario Series (207, 208, 209, 210, 211)
• 300 Vario Series (COM III)
• 400 Vario Series (409, 410, 411, 412 COM III)
• 700 Vario Series (711, 712, 714, 716, 718, 720, 722, 724)
• 800 Vario Series (815, 817, 818, S4)
• 900 Vario Series (916, 920, 922, 924, 926, 927, 930, 933, 936, 942)

1. 1

   Check the wiring harness and connectors (X2036 for Y173 or X1153 for Y088) leading to the trailer brake release solenoid valve for short circuits to ground, short circuits to +UB (battery voltage), or breaks.

2. 2

   Use the SERDIA diagnostics program to perform a functional test of the Y173/Y088 actuator to see if it clicks or draws incorrect current.

3. 3

   Verify the operation of the ABV activation button on the right/left dashboard control panel (A128), as a faulty button can trigger related ABV bypass faults.

4. 4

   Ensure the hydraulic system pressure is correct (typically 0...140 bar for the trailer brake circuit) and that there is no air in the Pentosin brake system circuit.

1. 1

   Preparation

   Park the tractor on a level surface, secure it to prevent rolling (chock the wheels), and switch off the ignition.

2. 2

   Access the Valve

   Remove the necessary panels (e.g., steering column panel or side access panels) to reach the hydraulic trailer brake valve (ABV) block.

3. 3

   Inspect and Replace Solenoid

   Locate the Y173 or Y088 solenoid valve on the ABV block. Disconnect the electrical harness. If the electrical diagnostic tests confirmed the solenoid coil is dead or shorted, unthread the faulty solenoid valve from the block and install the replacement.

4. 4

   Hydraulic Bleeding

   If the entire trailer brake valve block is replaced or hydraulic lines are opened, you must bleed the Pentosin brake system circuit to remove any air.

5. 5

   Reassembly and Clearing Codes

   Reconnect the electrical harness, reinstall all panels, and use the SERDIA tool to clear the 0A.1.EC fault code from the memory. Test the handbrake and footbrake to ensure the trailer brake releases properly.