Case IH 12022 – Instrumentation Controller (INST2) or Armrest Controller (ARM): Communications Lost with Aux67 Controller

The tractor's main communication network (CAN bus) has stopped receiving data messages from the AUX67 controller, which is the module responsible for operating Remote Valve Sections 6 and 7.

• STX Steiger
• STX Steiger Series
• STX275
• STX280
• STX325
• STX330
• STX375
• STX380
• STX425
• STX430
• STX450
• STX480
• STX530
• Quadtrac / Rowtrac Series
• MX Magnum & TG Series

1. 1

   Verify that the tractor model configuration is correct in the instrumentation controller using the display or EST to check 'ST MODEL' parameters

2. 2

   Locate the AUX67 controller and check for a status LED (a flashing green light typically indicates the board is receiving power and operating)

3. 3

   Test CAN bus voltages at the controller using a multimeter (expect approximately 2.5V on CAN High/yellow and 2.4V on CAN Low/green)

4. 4

   Verify that the AUX67 controller is receiving a steady 12V supply and has a clean, solid ground connection

5. 5

   Inspect harness connectors between the Armrest/Instrumentation controller and the AUX67 controller for backed-out pins, corrosion, or moisture

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical shorts.

2. 2

   Access the Controller

   Locate the AUX67 controller (typically located near the rear remote valve stack or in the rear cab electrical compartment).

3. 3

   Inspect and Clean

   Disconnect the wiring harness from the AUX67 controller. Clean the contacts with electrical contact cleaner and ensure no pins are bent or pushed back into the connector housing.

4. 4

   Test the Harness

   Reconnect the battery and turn the key to the ON position. Use a multimeter to verify 12V power and ground at the harness connector. Test the CAN bus wires for continuity back to the Instrumentation Controller.

5. 5

   Replace the Controller

   If the wiring harness tests good (power, ground, and CAN continuity are present) but communication is still lost, the AUX67 controller has suffered an internal hardware failure and must be replaced. Remove the mounting hardware and install the new module.

6. 6

   Calibrate and Clear

   Connect the Case IH Electronic Service Tool (EST). You must configure the new AUX67 controller to the tractor's network, perform a remote valve calibration, and clear the 12022 fault code from the Instrumentation Controller's memory.