Case IH 17661 (F-1231-11) - ECU – Engine Control Module (ECM) or Vehicle Controller (CCM): CAN Bus 1 is not functional (cannot transmit or receive messages)

The CAN Bus 1 network is offline or experiencing severe communication errors. This means the controllers on this specific bus cannot talk to each other. This is rarely a module failure; it is almost always a physical layer issue such as damaged wiring, disconnected/corroded connectors, moisture intrusion, or a failed terminating resistor.

• VESTRUM CVX
• Farmall Series (40-45-50 CVT, 95U, 105U, 115U Pro EP)
• Puma Series (165, 180, 195, 210, 215, 225 CVX)
• Magnum Series (MX180, MX210, MX240)
• Maxxum Series (120)
• Steiger Series

1. 1

   Verify if the fault is currently active. If it is intermittent, suspect moisture or a loose connection.

2. 2

   Inspect the CAN Bus 1 wiring harness and connectors for chafed wires, broken connector locks, or pushed-back pins.

3. 3

   Use the Electronic Service Tool (EST) to monitor which CAN networks are offline.

4. 4

   Perform a CAN Bus resistance test with the key switch OFF at the diagnostic connector (between CAN High and CAN Low pins). A normal reading is 54 - 66 Ω.

5. 5

   If the resistance reading is incorrect (~120 Ω or Open/OL), disconnect the wiring harness from the ECU and measure resistance directly at the harness pins to isolate the terminating resistors.

1. 1

   Disconnect Power

   Disconnect the battery to prevent electrical spikes during harness repair.

2. 2

   Locate Terminators

   Locate the two CAN Bus 1 terminating resistors. Typically, one is located near the engine controller (ECU) under the hood, and the other is located in the cab behind the standard instrumentation controller or inside the armrest.

3. 3

   Repair Wiring

   If the resistance test indicated an open circuit, trace the CAN Bus 1 harness (often yellow and green wires carrying ~2.4V to 2.5V). Repair any chafed or broken wires using OEM-approved splices and heat shrink.

4. 4

   Clean Connectors

   Disconnect the CAN Bus 1 connectors, spray with electrical contact cleaner to remove moisture/corrosion, and apply dielectric grease if specified by the manual. Ensure the locking tabs click securely into place.

5. 5

   Replace Terminators

   If a terminating resistor bench-tests outside of the 120 Ω specification, replace it.

6. 6

   Clear Codes

   Reconnect the battery, turn the key ON, and use the EST to clear the fault codes. Verify that CAN Bus 1 is back online and the fault does not return.