Case IH 520528-03 - ITBV – Trailer Brake Control (iTBV) module or Driveline Electronic Control (DEC) / Transmission controller: Trailer brake inlet/outlet valve ground voltage high

The controller is detecting that the ground circuit for the trailer brake inlet/outlet valve is seeing high voltage, meaning the ground path is likely shorted to a 12V power source or the valve's internal solenoid has failed and is bleeding voltage into the ground return.

• MAGNUM AFS Connect
• Case IH Magnum Series (180, 200, 220, 240, 250, 280, 310, 340, 380)
• Case IH Puma Series (185 - 260 CVX)
• Case IH Optum Series
• Case IH Maxxum Series

1. 1

   Check the power supply fuses for the ITBV system to ensure a blown fuse isn't causing a voltage backfeed. Inspect Fuse F-030 (10 A). For pneumatic setups, also check F-601 (15 A) and F-602 (15 A) in the EPDU power box.

2. 2

   Inspect the transmission wiring harness for chafing, melted insulation, or pinched wires that could cause the valve's ground wire to short against a 12V power wire.

3. 3

   Disconnect the electrical connector at the ITBV, turn the key ON, and use a multimeter to check the ground pin on the harness side. If it shows 12V, the wiring harness is shorted. If it shows proper ground, the short is likely internal to the ITBV solenoid.

1. 1

   Power down the tractor and turn off the battery disconnect switch.

2. 2

   Locate the Intelligent Trailer Brake Valve (ITBV) assembly.

   It is typically mounted near the transmission/air reservoir area.

3. 3

   Disconnect the electrical harness from the ITBV solenoid.

4. 4

   Repair the wiring harness if shorted.

   If the diagnostic checks proved the harness is shorted, trace the transmission/ITBV wiring harness back to the DEC/iTBV module, locate the short, and repair the wiring.

5. 5

   Relieve any pneumatic or hydraulic pressure from the trailer brake lines.

   Perform this if the harness is good, indicating the ITBV solenoid has failed internally.

6. 6

   Disconnect the air/hydraulic hoses from the ITBV.

   For example, the ITBV to Solenoid Valve tube.

7. 7

   Unbolt and remove the faulty ITBV assembly.

8. 8

   Install the replacement ITBV.

   Reconnect the pneumatic/hydraulic lines, and plug in the electrical connector.

9. 9

   Clear the fault codes and test the trailer brakes.

   Clear the fault codes via the AFS Pro display or Electronic Service Tool (EST) and test the trailer brakes to ensure the code does not return.