Case IH 12043 – INST (Instrumentation Controller) or ICU (Instrument Cluster Unit): Communications Lost with Vehicle Data Bus 1 and ALL other controllers

The instrumentation controller has detected that it can no longer communicate with the tractor's CAN Data Bus. The primary failure modes are: 1. The Data Bus is not powered. 2. The Data Bus is shorted. 3. A passive CAN terminator has failed.

• MX Magnum
• STX Steiger
• Magnum Series
• Boxcar Magnums
• 215
• 235
• 245
• 275
• 305
• 340
• TG Series
• Steiger Series
• Puma Series

1. 1

   Inspect CAN Connectors: Check the CAN bus connectors for moisture, dirt buildup, or aging.

2. 2

   Verify Controller Connection: Ensure the instrumentation controller is securely and properly connected to the Data Bus.

3. 3

   Check Bus Power: Verify that the Data Bus is receiving proper voltage and is powered.

4. 4

   Check for Shorts: Test the Data Bus wiring harness to ensure it is not shorted to ground or power.

5. 5

   Test the Passive Terminator: Check the CAN bus terminator resistor to ensure it has not failed (it should typically read 120 Ohms).

6. 6

   Check Controller Function: Verify the overall function of the instrument controller to rule out an internal failure of the cluster itself.

1. 1

   Disconnect battery

   Disconnect the battery to ensure safety while working on the electrical system.

2. 2

   Locate components

   Locate the CAN bus connectors and the instrumentation controller harness.

3. 3

   Inspect and clean connectors

   Disconnect the harnesses and inspect the pins for corrosion, pushed-back pins, or moisture. Clean and dry the connectors if necessary.

4. 4

   Test and replace terminator

   Locate the CAN bus passive terminator(s) on the harness. Use a multimeter to measure the resistance across the terminator. If it does not meet the required specification (120 Ohms), replace the terminator.

5. 5

   Inspect and repair wiring

   Inspect the wiring harness for chafing or bare wires that could cause a short circuit in the Data Bus. Repair any damaged wiring.

6. 6

   Reconnect and power on

   Reconnect all harnesses and power the tractor on.

7. 7

   Replace instrumentation controller

   If the code persists and the wiring/terminators are verified good, the instrumentation controller (instrument cluster) has likely failed internally and must be replaced or sent out for remanufacturing.