Case IH 520704-13 - ITBV – Trailer Brake Control Module (iTBV ECU): Reservoir pressure low

Indicates a low pressure condition in the reservoir of the ITBV (Intelligent Trailer Braking Valve) system. The pneumatic or hydraulic pressure available to actuate the trailer brakes has dropped below the minimum safe operating threshold.

• MAGNUM AFS Connect
• Case IH AFS Connect Magnum Series 180, 200, 220, 240, 250, 280, 310, 340, 380 (Tier 4B)
• Case IH Puma Series 125, 165, 180, 195, 210, 225 CVX
• Case IH Maxxum Series 140
• Case IH Steiger Series 535

1. 1

   Perform a manual pressure test by connecting a 0 to 40 bar diagnostic pressure gauge to the trailer brake coupler (using CNH fitting adapter no. 293190) to verify the actual physical pressure in the system.

2. 2

   Visually inspect the pneumatic/hydraulic tubes connecting the ITBV to the solenoid valve and the reservoir for chafing, cracks, or loose fittings that could cause a pressure leak.

3. 3

   Check the Trailer Brake Low Pressure Switch/Sensor and its wiring harness. If the manual gauge shows good pressure but the ECU reads low, the sensor or wiring is likely faulty.

4. 4

   Verify the ITBV ECU software version using the diagnostic tool to ensure it is running the latest version (e.g., software part number 51595354).

1. 1

   Depressurize the System

   Safely park the tractor on level ground, turn off the engine, and actuate the brake pedals repeatedly to relieve any residual pressure in the hydraulic/pneumatic trailer brake circuit.

2. 2

   Address Leaks

   If the visual inspection revealed a leaking tube (commonly the tube from the limiting valve to the ITBV or the ITBV to the solenoid valve), disconnect the fittings, remove the damaged line, and install the replacement tube. Torque fittings to OEM specifications.

3. 3

   Replace the Pressure Sensor

   If the physical pressure is fine but the fault persists, locate the trailer brake pressure sensor on the ITBV manifold. Disconnect the wiring harness, unthread the old sensor, and install the new one.

4. 4

   Replace the ITBV Valve / ECU

   If the system cannot build pressure and the pump/priority valve is functioning correctly, the ITBV valve itself may be bypassing internally. Disconnect the hydraulic/pneumatic lines and the electrical connectors from the ITBV ECU. Unbolt the ITBV assembly from its mounting bracket (usually located under the cab or near the priority valve) and install the new ITBV valve/ECU assembly.

5. 5

   System Bleed and Test

   Start the tractor and allow the system to build charge pressure. Check for leaks at any replaced fittings.

6. 6

   Clear Codes

   Connect the CNH diagnostic tool, clear the 520704-13 fault code, and perform a stationary parking brake/trailer brake engagement test to ensure the pressure holds and the code does not return.