Case IH 1086 – ATC, ARU, or ICU: No communication with the PMU controller.

The CAN (Controller Area Network) data bus has lost the communication signal from the PMU (Performance Monitor Unit).

• Magnum
• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 315
• Magnum 340
• MX180
• MX200
• MX210
• MX220
• MX230
• MX240
• MX255
• MX270
• MX285

1. 1

   Check that the PMU is receiving both switched and unswitched power by inspecting the cab/instrumentation fuses (often Fuse 36 or 37) and verifying the clean ground connection to the chassis.

2. 2

   Inspect the PMU harness (Connector 62M or 62F) for pushed-out pins, corrosion, or moisture.

3. 3

   Test the CAN bus integrity using a multimeter to check resistance across the CAN High and CAN Low lines at the PMU connector with the battery disconnected (should read 60 ohms; 120 ohms indicates an open circuit or failed terminating resistor).

4. 4

   Perform a hard reset to ensure the software is not locked up by disconnecting the battery for 15 minutes.

1. 1

   Disconnect Power

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

2. 2

   Access the PMU

   Locate the Performance Monitor Unit in the cab (typically mounted on the right-hand console or A-pillar, depending on the cab configuration).

3. 3

   Remove the Module

   Remove the plastic trim or mounting bracket screws securing the PMU.

4. 4

   Disconnect Harness

   Carefully unplug the multi-pin electrical connector (Connector 62) from the back of the unit.

5. 5

   Install New PMU

   Connect the wiring harness to the replacement PMU and secure it into the mounting bracket.

6. 6

   Reassemble and Power Up

   Reinstall all trim pieces and reconnect the negative battery cable.

7. 7

   Calibration/Programming

   Turn the key to the ON position. Connect the Case IH Electronic Service Tool (EST) laptop to flash the correct firmware to the new PMU and clear the inactive 1086 fault code.