Case IH 14902 – Auxiliary Controller: Auxiliary Controller Missing

The main vehicle computer has lost CAN bus communication with the Auxiliary Controller. This indicates the module is unpowered, unplugged, experiencing a CAN network wiring fault, or has failed internally. The Auxiliary Controller is responsible for managing optional implement controls, electronic draft control (EDC), and electro-hydraulic remote valves.

• Puma/Mid Range Magnum
• Maxxum
• Puma 140
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225
• Magnum MX210
• Magnum MX230
• Magnum MX255
• Magnum MX285
• Steiger
• Farmall

1. 1

   Check for accompanying codes (e.g., 12021, 14904, 14908) which may indicate the entire CAN bus is down due to a short circuit elsewhere.

2. 2

   Verify the Auxiliary Controller is receiving switched power, unswitched power (B+), and has a clean ground (check for blown fuses or bad grounds).

3. 3

   Inspect the Auxiliary Controller connectors for pushed pins, corrosion, or moisture.

4. 4

   Test the CAN bus resistance across the CAN High and CAN Low pins at the module connector with the battery disconnected (should read approximately 60 ohms; 120 ohms indicates a broken terminating resistor or CAN wiring segment).

1. 1

   Disconnect power

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

2. 2

   Access the module

   Remove the interior cab trim panels (usually right-hand rear) or exterior access panels required to reach the Auxiliary Controller.

3. 3

   Disconnect harness

   Carefully unplug the multi-pin connectors from the module. Tag the hydraulic lines if working on a model where the controller is integrated directly into the remote valve block.

4. 4

   Remove the module

   Remove the mounting bolts securing the controller to its bracket and remove the unit.

5. 5

   Install the new module

   Mount the replacement Auxiliary Controller and tighten the hardware to OEM torque specs.

6. 6

   Reconnect wiring

   Apply a light coat of dielectric grease to the connector seals (do not pack the pins) and firmly seat the wiring harness.

7. 7

   Calibrate and configure

   Reconnect the battery. Configure the new module via the instrument cluster H-menus (e.g., H1, H8) or by using the Case IH Electronic Service Tool (EST) laptop to flash the correct software.