Case IH 2254 – ZDC Controller: ZDC - CAN message ExtPoti00 checksum incorrect

A CAN bus communication error regarding a specific external potentiometer signal (ExtPoti00). The data packet containing this potentiometer's position was corrupted during transmission across the CAN network, causing the receiving module to flag the message as faulty and typically default the value to 0% or limit the vehicle's maximum speed.

• Steiger T4B
• Case IH Steiger CVT / AFS Connect CVT
• Case IH Puma CVX / CVXDrive
• Case IH Maxxum CVX
• Case IH Magnum CVT

1. 1

   Verify the physical operation of the cab potentiometers (hand throttle, clutch pedal, and multi-function handle/drive lever) for physical damage, sticking, or dead spots in the travel.

2. 2

   Inspect the fuses powering the ZDC controller (e.g., F-101 or F-102 for Steiger models) and the cab controllers.

3. 3

   Measure the CAN bus resistance at the diagnostic port (should be approximately 60 ohms). A reading of 120 ohms indicates a broken CAN wire or missing terminating resistor.

4. 4

   Inspect the wiring harness between the cab control modules and the ZDC controller for chafing, pinched wires, or corroded connector pins.

1. 1

   Access the Cab Controls

   Remove the trim panels to access the wiring for the hand throttle, clutch pedal, and armrest drive lever.

2. 2

   Test the Potentiometer (ExtPoti00)

   Using a multimeter, sweep the suspected potentiometer (throttle/clutch) while monitoring the resistance or voltage output. The signal should change smoothly without any dropouts or spikes. If a dropout occurs, the potentiometer is faulty.

3. 3

   Inspect the ZDC Connectors

   Locate the ZDC controller (usually mounted externally on the transmission or under the cab floor depending on the model). Disconnect the harness and inspect for moisture, bent pins, or corrosion. Clean with contact cleaner if necessary.

4. 4

   Perform Continuity Check

   Pin out the CAN High and CAN Low wires from the cab controller to the ZDC controller. Repair any open circuits or shorts to ground/power.

5. 5

   Replace Faulty Component

   If the wiring is intact but the CAN message remains corrupted, replace the faulty potentiometer or the module broadcasting the ExtPoti00 signal.

6. 6

   Clear Codes and Calibrate

   Use the Case IH Electronic Service Tool (EST) to clear the fault code. If a potentiometer was replaced, perform the end-to-end calibration procedure for the throttle or clutch pedal.