(h) When any of the following malfunctions occur, CAN
communication cannot be established and almost all ECUs and
sensors on the bus show a communication error on the CAN Bus
Text in Illustration
*a When any of the following malfunctions occur on the V bus
*b When any of the following malfunctions occur on a sub bus
*c Not displayed
Details of Malfunction
Short between CAN lines (CANH and CANL)
Short between a CAN line (CANH or CANL) and +B
Short between a CAN line (CANH or CANL) and ground
Open in a CAN main bus line
hen a malfunction occurs on the V bus, almost all ECUs and
sensors on the V bus and sub bus indicate a communication error
(almost all ECUs are not displayed). As communication with the
gateway function equipped ECU that is connected to the V bus
stops, communication from the ECUs connected to the sub bus
that is monitored by the gateway function equipped ECU also
stops (these ECUs are not displayed).
When a malfunction occurs in a sub bus, almost all ECUs
connected to the sub bus indicate a communication error.
A communication error in a sub bus does not affect the V bus or
The malfunctioning part can be determined by checking for a
short circuit between CAN bus lines or between a CAN bus line
and ground or +B short using an electrical tester.
5. HOW TO INTERPRET COMMUNICATION DTCS (DTCS THAT START WITH U)
(a) If a CAN communication error cannot be reproduced, determine the suspected malfunctioning part using
the DTCs stored in ECUs that are connected to the CAN buses by following the procedure below.
Communication DTCs (DTCs that start with U) indicate a communication error between the ECU that stores
the DTC and the ECU that is indicated by the DTC.
(1) If multiple ECUs store a communication DTC for a particular ECU, a communication stop of the ECU is