Case IH 520527-04 - ITBV – ITBV: Back up valve - Voltage Below Normal, or Shorted to Low Source

The system has detected a "voltage low" condition, which typically means there is a short circuit to ground (GND) in the active or inactive state of the backup valve solenoid circuit.

• MAGNUM AFS Connect
• Case IH AFS Connect Magnum Tractors (Models 180, 200, 220, 240, 250, 280, 310, 340, 380) with CVT or Full Power Shift transmissions (Tier 4B)
• Case IH Farmall tractors with Cab and CVT transmissions

1. 1

   Visual Inspection: Inspect the wiring harness running from the ITBV Electronic Control Unit to the backup valve solenoid. Look for chafing, pinched wires, or melted insulation that could cause a short to ground.

2. 2

   Connector Check: Disconnect the harness at the backup valve and at the ITBV module. Check for water intrusion, corrosion, or bent pins.

3. 3

   Circuit Testing (Short to Ground): Using a multimeter, check for continuity between the backup valve power supply wire and the chassis ground. If continuity exists, the wiring harness is shorted.

4. 4

   Component Testing: If the wiring harness tests good, measure the internal resistance of the backup valve solenoid. An internal short inside the solenoid coil will also pull the voltage low and trigger FMI 04.

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Isolate the Fault

   Disconnect the wiring harness from the ITBV backup valve solenoid.

3. 3

   Repair Wiring (If Applicable)

   If your multimeter tests showed a short to ground in the harness, trace the wire back to the ITBV module. Repair the chafed section of the wire using OEM-approved heat-shrink connectors, or replace the affected harness section.

4. 4

   Replace the Valve (If Applicable)

   If the harness is intact but the solenoid is internally shorted, the valve must be replaced. Relieve any residual pneumatic/hydraulic pressure in the trailer brake lines. Disconnect the hydraulic/pneumatic tubes (e.g., the tube from the shuttle valve to the backup valve). Unbolt the faulty backup valve/solenoid and install the new unit. Reconnect the lines and torque to OEM specifications.

5. 5

   Reassembly and Testing

   Reconnect the electrical harness and the battery. Turn the key to the ON position, clear the inactive fault codes using the diagnostic tool, and actuate the trailer brakes to ensure the code does not return and line pressure is correct.