Communication error on Automation B CAN bus. CAN-bus buffer overflow.
Check connector for Automation B CAN-bus on ACUB1 (pin B3 and B12). • Check wiring for CAN-bus: - Measure the resistance (with the battery disconnected) between CAN-high (pin B3) and CAN-low (pin B12). It should be close to 60 ohm (one 120 ohm termination resistor in each end of the CAN-bus). - Measure the resistance (with the battery disconnected) between CAN-high on ACUB1 (pin B3) and CAN-high on any other unit on the expansion CAN-bus. It should be close to zero ohm. - Measure the resistance (with the battery disconnected) between CAN-low on ACUB1 (pin B12) and CAN-low on any other unit on the expansion CAN-bus. It should be close to zero ohm.
What you'll see
No driver-visible symptom recorded.
System reaction
• Functions dependent on information on the Automation B CAN bus from ACUB1 might be degraded. Examples listed below. - Degraded autonomous function.
Diagnostic depth
The fault is validated as present if the ECU tries to send CAN-messages on the Automation B CAN bus, but no acknowledge is received from other units, and thereby causing the internal send buffer (in the ECU) to overflow. The DTC is set to active if the buffer overflow has lasted for 50 ms. The DTC is set to inactive when the CAN-messages are sent properly again and the buffer no longer is overflowing for the last 1050 ms. The DTC is not validated (stored) if: • the ignition is turned off • first 2 seconds after ignition on • the supply voltage is below 22 volt • the supply voltage is above 32 volt • short circuit on expansion CAN-bus (separate DTC)
• Defect connectors on ACUB1 for Automation B CAN bus (pin B3 or B12). • Defect wiring for CAN-bus, open circuit on CAN-high (pin B3) or CAN-low (pin B12).