Case IH PAE – Transmission Control Unit (TCU) or main vehicle controller: Vehicle CAN Chip, Data Valid But Above Normal Range

Indicates a communication anomaly on the Controller Area Network (CAN) bus. The CAN chip is successfully processing data packets (the data is valid and not corrupted), but the specific values or signals being transmitted/received are falling above the expected normal operating threshold.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190

1. 1

   Scan for companion codes (such as TB0, TB1, or TB2) using the Case IH Electronic Service Tool (EST) to isolate if the issue is a wiring short versus a module failure

2. 2

   Visually inspect the CAN bus wiring harnesses and connectors (such as the 21-pin aluminum Deutsch connectors) for corrosion, moisture, or backed-out pins

3. 3

   Use the EST protocol adapter to monitor controller status and retrieve freeze-frame data to see the exact conditions when the CAN chip registered the out-of-range data

1. 1

   Connect Diagnostic Equipment

   Plug the Case IH EST into the tractor's diagnostic port to pull active and stored codes, and access the digital electrical schematics for your specific model.

2. 2

   Test the CAN Network

   Probe the CAN-High and CAN-Low lines with a multimeter to verify network resistance (typically 60 ohms) and check for voltage irregularities that might be pushing the data out of range.

3. 3

   Repair Wiring/Filters

   If wiring damage or a failed EMI filter is found, repair the harness or replace the filter.

4. 4

   Replace the Controller

   If the wiring harness tests perfectly, the fault lies internally within the CAN chip on the microprocessor. The non-volatile memory controller or the entire ECU will need to be replaced.

5. 5

   Perform Transmission Calibration

   If the microprocessor is replaced or a mechanical repair is effected, you must perform the Transmission/EDC Calibration. Block the wheels and place all shift levers in neutral. Hold the High and Low range buttons and start the engine until 'CAL' appears on the transmission display. Set the engine speed to 1200 ERPM (±100) and follow the on-screen prompts to calibrate the clutches.