Case IH 12558 – MTA CCM & APH STAGE V MR: Handbrake load sensor short to GND or open circuit.

The control module has detected an electrical fault in the handbrake load sensor circuit. The circuit is either physically broken (open circuit) or the signal wire is shorting out to the ground, preventing the module from reading the handbrake's load/position status.

• MAXXUM T4E
• Farmall 40
• Farmall 45
• Farmall 50
• Farmall 115U Efficient Power

1. 1

   Inspect the wiring harness connecting the handbrake load sensor to the CCM for any visible damage, chafing, or pinched wires

2. 2

   Disconnect the sensor and inspect the connector pins for corrosion, moisture ingress, or pushed-out pins

3. 3

   Using a multimeter, test the signal wire between the sensor connector and the CCM for continuity to rule out an open circuit

4. 4

   Check the signal wire for continuity to ground to rule out a short to GND

5. 5

   Test the sensor itself to verify it provides the correct variable resistance or voltage signal when the handbrake is actuated

1. 1

   Park the tractor on a level surface, turn off the engine, and securely chock the wheels

   This is required since you will be working on the parking brake system.

2. 2

   Locate the handbrake load sensor/switch assembly

   Typically mounted near the base of the handbrake lever or along the parking brake linkage.

3. 3

   Disconnect the electrical connector from the sensor

4. 4

   Repair the broken wire or shorted section of the harness using appropriate weatherproof splices, or replace the damaged connector pigtail

   Perform this step if the wiring is faulty.

5. 5

   Remove the mounting hardware securing the handbrake load sensor and remove the unit

   Perform this step if the sensor is faulty.

6. 6

   Install the new handbrake load sensor and secure it with the mounting hardware

7. 7

   Reconnect the electrical connector

8. 8

   Turn on the ignition and use a diagnostic tool to clear the fault codes

   Actuate the handbrake several times to verify that the code does not return and the dashboard park brake indicator functions correctly.