Case IH 19639 – eXBR1 (Electronic Trailer Brake Controller) / EBM (Electronic Brake Module): Short circuit to ground in the high side of the pressure control valve

The high side (the power supply circuit) of the pressure control valve solenoid has shorted to a ground source, preventing the valve from operating correctly and potentially blowing a fuse or triggering a module protection shutdown.

• Tier 4b
• Puma 195
• Puma 230
• Puma 240 CVT
• Maxxum 115
• Optum series

1. 1

   Inspect the wiring harness running from the eXBR1 controller to the trailer brake pressure control valve for chafed insulation, pinched wires, or rubbing against the chassis

2. 2

   Disconnect the electrical connector at the pressure control valve and use a multimeter to check the high-side (power) pin on the harness side for continuity to ground (indicates a harness short)

3. 3

   Test the pins on the pressure control valve for continuity between the high-side pin and the metal body of the valve (indicates an internal solenoid short)

4. 4

   Check for accompanying eXBR1 CAN communication codes (such as 12702 through 12709) to verify if the module has shut down or blown a dedicated fuse

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Locate the Valve

   Locate the trailer brake pressure control valve. On Case IH Puma and Maxxum tractors, this is typically mounted under the cab on the priority valve block, which sits at the top of the main hydraulic pump unit.

3. 3

   Isolate the Short

   Based on your diagnostic checks, isolate whether the short is in the harness or the valve.

4. 4

   Repair Wiring (If Applicable)

   If the harness is shorted to the chassis, splice in a new section of wire using weather-sealed heat-shrink connectors, or replace the affected harness section. Route the wire away from sharp edges or high-heat areas.

5. 5

   Replace the Valve (If Applicable)

   If the valve solenoid is internally shorted: Clean the area around the valve, relieve any residual hydraulic pressure, disconnect the hydraulic lines and remove the mounting bolts. Install the new pressure control valve with new O-rings and torque the mounting bolts to OEM specifications.

6. 6

   Reassembly and Testing

   Reconnect the electrical connector and the battery. Start the tractor, clear the fault codes using a diagnostic tool, and depress both brake pedals simultaneously to actuate the trailer brakes. Verify that code 19639 does not return.