Absence of CAN1 sub-bus communication (buffer overflow). CAN1 is TMS Sub-bus except for Battery slave units (BSU:s) where CAN1 is BMU Sub-bus.
• Check connector for sub-bus on BMU(E81) pin B29 and B32. • Check wiring for sub-bus: - Measure the resistance on the connector to BMU(E81) (with the 24V battery disconnected) between CAN-high (pin B29) and CAN-low (pin B32). It should be close to 60 ohm (one 120 ohm termination resistor in each end of the CAN-bus). - Measure the resistance on the connector to BMU(E81) (with the 24V battery disconnected) between CAN-high on BMU(E81) pin B29 and CAN-high on any other unit on the same CAN-bus. It should be close to zero ohm. - Measure the resistance on the connector to BMU(E81) (with the 24V battery disconnected) between CAN-low on BMU(E81) pin B32 and CAN-low on any other unit on the same CAN-bus. It should be close to zero ohm. • Check wiring and connector for the ignition signal (pin B38) on the BMU. • If no other errors can be found, change BMU(E81).
What you'll see
No driver-visible symptom recorded.
System reaction
• For TMS sub-bus VOR will occur, the hybrid system will not work since the battery will not be engaged. The DCC will not receive VCB-power and the 24-volt system will drain the 24-volt batteries. • Amber warning lamp "Hybrid System Fault" is shown in ICL
Diagnostic depth
The fault is validated as present if the ECU tries to send CAN-messages on the sub-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
• Defect connectors on BMU(E81) for sub-bus (pin B29 or B32) • Defect wiring for the sub-bus, open circuit on CAN-high (pin B29) or CAN-low (pin B32). • Ignition signal (pin B38) on BMU(E81) is short circuit to supply.