Case IH 1087-00 - ITBV – ITBV: Trailer brake control line pressure disagreement - pressure high

The actual pneumatic or hydraulic pressure measured on the trailer brake control line is higher than the expected or commanded pressure calculated by the controller. The system detects this incongruence during a plausibility check of the pressure controller.

• MAGNUM AFS Connect
• Case IH AFS Connect Magnum Tractors (Models 180, 200, 220, 240, 250, 280, 310, 340, 380)

1. 1

   Sensor Plausibility Check: Verify the output of the trailer brake control line pressure sensor. Ensure it is not reading artificially high due to a sensor failure.

2. 2

   Wiring Harness Inspection: Check the ITBV wiring harness for electrical faults. The system specifically monitors for a 'Short to Power', 'Short to Ground', or 'Interruption/Low Current' at the Inlet Valve (IV) and Outlet Valve (OV).

3. 3

   Brake Pedal Switch Check: Perform a plausibility check on the brake pedal output to ensure the brake switch and demand pressure sensors are not sending conflicting signals (e.g., brake switch low but demand pressure high).

4. 4

   Pneumatic/Hydraulic Line Inspection: Inspect the air reservoir, drain valves, and the trailer brake tubes for blockages or mechanical restrictions that could trap pressure in the control line.

1. 1

   Depressurize the System

   Safely relieve all pneumatic and hydraulic pressure from the tractor's trailer brake system and air reservoirs before servicing.

2. 2

   Inspect and Test the Pressure Sensor

   Locate the pressure sensor on the hydraulic/pneumatic trailer brake line. Test the sensor voltage; if it is shorted to power or reading out of spec, replace the sensor.

3. 3

   Inspect the ITBV Solenoids

   Check the Inlet Valve (IV) and Outlet Valve (OV) on the ITBV assembly. If the diagnostic tool indicates a high current or short at the inlet/outlet valves, the solenoid or the entire ITBV valve block may have failed internally.

4. 4

   Replace Faulty Components

   If the ITBV is mechanically sticking and causing high pressure, remove the pneumatic ITBV valve and install the replacement unit. Ensure the backup valve and connecting tubes (ITBV to Solenoid Valve) are clear of debris.

5. 5

   Clear and Calibrate

   Reconnect the wiring harnesses, power on the machine, and use the electronic service tool to clear the off-board fault stack. Perform any required calibration for the MTA CCM (Transmission/Chassis Control Module) and ITBV software.