Case IH 12993 – MTA CCM or UCM: Communication or test in external safety controller failed.

The primary control module has lost communication with an external safety controller or the safety controller has failed its internal self-test. This is tied to the pneumatic braking system and the Intelligent Trailer Brake Valve (iTBV).

• MAXXUM T4E
• Stage V MR (Medium Range)
• Farmall 40
• Farmall 45
• Farmall 50

1. 1

   Check for companion codes in the UCM or CCM, specifically code 12999 (iTBV fault code not recognized) or brake demand sensor faults, to isolate the exact subsystem.

2. 2

   Inspect the CAN bus communication lines between the CCM, UCM, and the external safety controller / iTBV for chafed wires, corrosion, or backed-out pins.

3. 3

   Verify the external safety controller is receiving proper operating voltage and has a clean ground to rule out voltage drops causing internal test failures.

1. 1

   Disconnect battery

   Disconnect the battery to ensure safety while working on the tractor's electrical and pneumatic systems.

2. 2

   Locate controller

   Locate the external safety controller / Intelligent Trailer Brake Valve (iTBV) on the tractor chassis.

3. 3

   Test CAN bus wiring

   Disconnect the main harness to the controller and use a multimeter to test the CAN High and CAN Low pins for proper resistance (typically 60 ohms across the bus) and check for continuity back to the CCM/UCM.

4. 4

   Repair wiring

   Repair any damaged wiring or replace the connector pigtail if corrosion is found.

5. 5

   Replace controller

   If the wiring harness tests good, the external safety controller itself has suffered an internal failure and must be replaced.

6. 6

   Calibrate and clear faults

   Install the new controller, reconnect the battery, and use the Case IH Electronic Service Tool (EST) to clear the fault stack and perform any required End-Of-Line (EOL) calibration tests for the pneumatic braking system.