New Holland 12132 – Armrest Control Unit (ARU) or Advanced Dashboard Information Center (ADIC): CAN Bus Is Disabled

A complete breakdown in communication on one of the vehicle's Controller Area Network (CAN bus) networks. The CAN bus is not functioning, which prevents communication between systems such as the engine controller, transmission controller, and armrest controller. This issue affects the operation of connected components, leads to the failure of multiple systems, and impacts the overall performance of the machine. Common symptoms include multiple unrelated fault codes appearing simultaneously, a 'No Communication' message on the dashboard display, specific modules (like GPS or hydraulic controller) becoming unresponsive, and diagnostic tools being unable to connect to one or more control modules.

• Tractors
• Combines
• Sprayers
• Construction Equipment

1. 1

   Perform a visual inspection of the main CAN bus network wiring harnesses for chafing, corrosion on connectors, pinched wires, or heat damage. Pay close attention to harness sections that pass near moving parts or hot components.

2. 2

   Check battery voltage and ensure all ground connections are clean and secure, as a low battery or poor ground can cause unpredictable electronic faults and communication errors.

3. 3

   Perform a wiggle test with the machine's key on by carefully wiggling connectors and sections of the wiring harness for the affected CAN network. If the fault appears or disappears, it strongly suggests a loose connection or a break in the wiring.

4. 4

   Perform a CAN bus resistance check with vehicle power completely OFF at a convenient point in the harness. Measure resistance between CAN High and CAN Low wires: ~60 Ohms indicates intact wiring and terminating resistors; ~120 Ohms indicates a missing resistor or open circuit; significantly less than 60 Ohms indicates a short circuit or extra resistors; Open Circuit (OL) indicates a break in the wiring.

1. 1

   Isolate the fault

   If the resistance measurement is incorrect, isolate the faulty part of the circuit. Using a wiring diagram, disconnect modules one by one, re-measuring the resistance each time. If the resistance returns to a normal value after disconnecting a specific module, that module or its connector is the likely source of the problem.

2. 2

   Check terminating resistors

   If the resistance measures ~120 ohms, it indicates a missing terminator or a break in the line. Check the wiring diagram to locate both terminators (which may be integrated into a module or use a separate dummy plug) and ensure they are present and functioning.

3. 3

   Repair wiring

   If a wiring fault (open or short circuit) is identified, repair the damaged section. It is critical that the wire lengths are not significantly altered, as this can affect the performance of the CAN bus system.

4. 4

   Check for faulty modules

   If the wiring and terminators are confirmed to be good, an internal module failure may be flooding the network with bad data or pulling the bus voltage out of specification. Disconnect modules one at a time until the rest of the network begins to communicate correctly.

5. 5

   Clear fault codes

   Once the repair is complete, reconnect all components and use the dashboard or the Electronic Service Tool (EST) to clear the fault codes.

6. 6

   Verify repair

   Start the machine and operate its systems to ensure that the fault does not return and that all modules are communicating correctly.