John Deere 002049.09 – SCC: CAB Message Missing

A fault has been detected in the CAN BUS message communication related to the rear chassis. The Selective Control Unit (SCC) is not receiving expected messages over the CAN bus from the Cab Control Unit (CAB). This indicates a failure in message transmission or reception, which is typically caused by wiring harness damage, power or ground loss to a module, or a failed controller on the network.

• 8130
• 8230
• 8230T
• 8330
• 8330T
• 8430
• 8430T
• 8530
• 8310RT
• 8335RT
• 8360RT

1. 1

   Visually inspect the wiring harness and connectors between the Cab Control Unit (CAB) and the Selective Control Unit (SCC) for chafing, pinching, corrosion, or moisture.

2. 2

   Check fuses (such as F22) to ensure there is no loss of power to the control units.

3. 3

   Inspect and clean the main ground connections for the chassis and cab controllers.

4. 4

   Perform a CAN bus resistance check at a diagnostic connector with vehicle power off. A healthy bus should read approximately 60 ohms. A reading of 120 ohms may indicate a missing terminating resistor or broken wire, while significantly lower than 60 ohms could indicate a short in the wiring or a faulty controller.

5. 5

   Perform a CAN bus voltage check with power on. CAN High (Yellow wire) should be 2.5-3.0 VDC; CAN Low (Green wire) should be 2.0-2.5 VDC relative to ground. Abnormal voltages can point to a short to power, a short to ground, or a failed transceiver in one of the control units.

1. 1

   Address other codes

   Diagnose and resolve any other active diagnostic trouble codes first, especially those indicating a loss of communication with other modules.

2. 2

   Isolate the fault

   If visual and basic electrical checks do not reveal the problem, disconnect other controllers on the CAN bus one by one to see if communication is restored, indicating a specific module is pulling the network down.

3. 3

   Repair wiring harness

   If a damaged section of the wiring harness is found, splice in new wire. Ensure connections are soldered and sealed with heat shrink tubing to prevent moisture intrusion.

4. 4

   Clean connectors

   If corrosion is found on connector pins, clean them carefully with an electrical contact cleaner and ensure a secure connection upon reassembly.

5. 5

   Replace faulty controller

   If diagnostics confirm wiring and connections are intact but the CAB controller is not sending messages or the SCC cannot receive them, replace the faulty controller.