Case IH 12968 – MTA CCM & APH (Chassis Control Module): Faulty input information regarding External park brake status

The control module is receiving an implausible, missing, or out-of-range electrical signal from the external parking brake switch/sensor, preventing the system from accurately determining if the parking brake is engaged or disengaged.

• MAXXUM T4E
• Case IH Farmall 40
• Case IH Farmall 45
• Case IH Farmall 50
• Farmall
• Maxxum

1. 1

   Check for related codes (such as 12969 or 12970) which could indicate a broader wiring harness issue

2. 2

   Inspect the external park brake switch near the parking brake linkage/lever for physical damage, heavy dirt/debris buildup, or misalignment

3. 3

   Inspect the wiring harness and connectors running from the park brake switch to the MTA CCM for chafed wires, corrosion in the pins, or loose connections

4. 4

   Test the switch for continuity using a multimeter; it should show a clear open/closed circuit transition when the parking brake is manually engaged and disengaged

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the negative battery terminal to prevent electrical shorts.

2. 2

   Locate the Switch

   Access the external park brake switch assembly (location varies slightly by cab configuration, typically along the mechanical brake linkage or at the base of the handbrake assembly).

3. 3

   Disconnect

   Unplug the electrical connector from the switch.

4. 4

   Remove

   Unscrew the mounting hardware (often a threaded body with a locking nut or a simple push-button bracket mount) and remove the faulty switch.

5. 5

   Install

   Thread or mount the new OEM parking brake switch into place. If it is a threaded switch, ensure it is adjusted to the correct depth so the linkage properly depresses the plunger without crushing it.

6. 6

   Reconnect

   Plug the electrical connector back into the switch and reconnect the battery.

7. 7

   Clear and Test

   Turn the key on, clear the fault codes from the CCM, and cycle the parking brake several times to ensure code 12968 does not return and the dash indicator functions correctly.