Case IH 12971 – MTA CCM (Central Control Module) and APH (Armrest/Cab Controller): Faulty input information regarding Primary vehicle velocity

The machine's control system is receiving an invalid, erratic, or missing signal regarding how fast the tractor is moving. This can cause a speedometer reading of 0.0 mph, erratic transmission shifting, or a complete loss of drive.

• MAXXUM T4E
• Maxxum
• Puma
• Magnum
• Optum
• Steiger
• Farmall
• T5
• T6
• T7
• T8

1. 1

   Check the Radar Unit (If Equipped): Unplug the radar unit; the system should default to reading the transmission speed sensor. If the speedometer starts working again, the radar unit is the culprit.

2. 2

   Inspect Sensor Wiring: Locate the transmission speed sensor and inspect the wiring harness and plug for dust, moisture, corrosion, or physical damage.

3. 3

   Check Battery Voltage: Ensure your battery and alternator are healthy, as low voltage (dropping below 11.5 volts) can cause erratic sensor readings and trigger false codes.

1. 1

   Power Down

   Disconnect the tractor's battery before swapping electronic sensors to prevent electrical shorts or network spikes.

2. 2

   Locate the Sensor

   Consult your specific model's service manual for the exact location. It is typically accessible externally on the transmission housing, output shaft, or rear axle.

3. 3

   Remove the Old Sensor

   Unplug the electrical connector. Remove the retaining bolt holding the sensor in the housing and pull the sensor straight out.

4. 4

   Install the New Sensor

   Insert the direct-replacement OEM sensor into the housing. Secure the retaining bolt and plug the weather-resistant connector back in.

5. 5

   Clear the Fault

   Reconnect the battery. Turn the key on and use the programmable display (Pro600/Pro700 or A-post monitor) to clear the fault. On standard instrumentation, you may need to depress the 'Reset' button.

6. 6

   Test Drive

   Operate the tractor to verify that the speedometer registers accurately and the transmission shifts smoothly without throwing the 12971 code.