Case IH 12819 – CCM (Chassis Control Module) or Trailer Brake Controller: Failure of brake sensor 1 supply 'Short to Ground'

The electrical supply circuit providing voltage to brake sensor 1 has shorted to the chassis ground, or the sensor itself has suffered an internal short, which can disable brake lights, trailer braking systems, and safety interlocks.

• MAXXUM T4E
• Farmall 85A/C
• Farmall 95A/C/U
• Farmall 105A/C/U
• Farmall 110U
• Farmall 115A/C/U
• Farmall 115U Pro
• Farmall 120U
• Maxxum 100
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 135
• Maxxum 140
• Maxxum 145
• Maxxum 150
• Magnum 180
• Magnum 190
• Magnum 200
• Magnum 210
• Magnum 220
• Magnum 225
• Magnum 240
• Magnum 315
• Puma Series
• Optum Series

1. 1

   Check the Fuse: Locate the fuse supplying the brake circuit (e.g., Fuse 38). Turn the key ON. If the fuse blows immediately, the short is constant. If it blows only when the brake pedal is depressed, the short is between the switch and the controller.

2. 2

   Isolate the Sensor vs. Harness: Unplug the connector(s) at the brake sensor(s).

3. 3

   Test for Ground: With the sensor unplugged, use a multimeter to check the supply wiring harness for continuity to the chassis ground.

4. 4

   Test the Sensor: If the harness tests OK (no short to ground), the internal resistor or diode inside the brake sensor body has likely failed and shorted internally.

1. 1

   Disconnect Power

   Disconnect the tractor's battery cables to prevent further electrical shorts or module damage during repair.

2. 2

   Locate the Sensor

   Find the brake sensor/switch. It is typically mounted directly on the brake pedal lever assembly, on a bracket next to it, or tucked under the dash/cab floor.

3. 3

   Remove the Faulty Sensor

   Disconnect the wiring harness pigtail from the sensor. Unclip or unbolt the sensor from its mounting bracket.

4. 4

   Harness Repair

   If your diagnostic checks revealed a harness short, trace the wire back from the sensor connector to the controller, looking for areas where the wire bends or rubs against the frame. Splice and repair the damaged wire using an approved electrical harness repair kit.

5. 5

   Install the New Sensor

   Fit the replacement brake sensor into the mounting location and secure it. Reattach the wiring harness connector.

6. 6

   Reassemble and Test

   Reconnect the battery. Turn the key ON and test the brake pedal. Verify that the brake lights illuminate, the tractor shifts out of park properly, and the 12819 fault code clears from the dashboard display.