Case IH 1012 – Hitch: No communication with the ACM (Armrest Controller Module)

Loss of CAN bus communication between the tractor's main controller and the module located in the armrest console.

• Magnum
• Steiger T4B
• Case IH Magnum 235 – 340 (Series 4)
• Case IH Steiger series
• Case IH Puma series

1. 1

   Check for related communication codes (such as 1013: No communication with the ICP). Multiple communication codes usually point to a main CAN bus wiring failure rather than a failed ACM.

2. 2

   Test the power supply and ground circuits going to the Armrest Controller Module. A blown fuse, bad relay, or corroded ground will cause the module to drop off the network.

3. 3

   Inspect the main harness connectors at the base of the armrest and at the Hitch/TCU controller for bent pins, moisture, or corrosion.

4. 4

   Use a multimeter to check the resistance across the CAN High and CAN Low pins (with the battery disconnected). It should read approximately 60 ohms. Check for continuity between the ACM connector and the main controller.

1. 1

   Disconnect Power

   Turn off the key and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Access the ACM

   Remove the plastic trim panels on the right-hand operator armrest console to expose the Armrest Controller Module and its wiring harness.

3. 3

   Perform Harness Repair (If Applicable)

   If the diagnostic checks revealed a broken wire, short to ground, or short to power on the CAN lines, repair the damaged section of the harness using OEM-approved splice kits and heat shrink.

4. 4

   Replace the ACM (If Applicable)

   If the wiring, power, and ground all test perfectly but the module still will not communicate, the ACM has failed internally. Disconnect the multi-pin connectors from the old ACM, unbolt it from the armrest chassis, and install the new module.

5. 5

   Reassemble and Calibrate

   Reconnect the battery. Turn the key to the ON position. You may need to use the Case IH EST (Electronic Service Tool) to clear the inactive 1012 fault code and flash/calibrate the new Armrest Controller Module to the tractor's main ECU.

6. 6

   Test Operation

   Verify that all armrest functions (throttle, hitch controls, PTO) are responding normally.