Check CAN Bus Lines for Short Circuit

CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: Check CAN Bus Lines for Short Circuit

Check CAN Bus Lines for Short Circuit

DESCRIPTION

The CAN bus wires are considered to be shorted when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ohms.






WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: Identify the connector to be checked by its color of the wire and shape of the junction on the CAN J/C because the locations of the connectors to the CAN J/C are confusing.

PROCEDURE

1. CHECK CAN BUS WIRE FOR SHORT CIRCUIT (DLC3 BRANCH WIRE)
(a) Turn the ignition switch to the LOCK position.




(b) Disconnect the DLC3 branch wire connector (J25) from the wiring harness connector (CAN J/C1).




(c) Measure the resistance according to the value in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE DLC3 BRANCH WIRE OR CONNECTOR (CAN-H, CAN-L)
OK -- Continue to next step.
2. CHECK CAN BUS WIRE FOR SHORT CIRCUIT
(a) Reconnect the DLC3 branch wire connector (J25) to the wiring harness connector (CAN J/C1).




(b) Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.
(c) While observing the resistance value shown on the tester, disconnect connectors J22, J23, J26, J49, J50(*1), and J51 from the CAN J/C1 one by one until the resistance becomes normal (between 54 and 69 Ohms).

















HINT:
(*1) : with dynamic laser cruise control system
NOTICE:
Do not reconnect the disconnected connectors until this inspection is complete because there may be a short in 2 or more branch wires.

Result:





(d) When there is a short in one or more of the branch wires:
(1) Reconnect all of the connectors to the CAN J/C, except for the one that was disconnected last (the short-circuited bus wire). Check that the resistance shown on the tester is normal (between 54 and 69 Ohms) to confirm that there is a short in the one branch wire only.
HINT:
- The connectors connected to the CAN J/C can be distinguished according to the color of the communication bus wires and the shape of the connectors.
- Reconnecting the connectors to non-specified positions on the CAN J/C does not affect system operation. However, it is preferred to reconnect the connectors to their specified positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

B -- CHECK CAN BUS WIRE FOR SHORT CIRCUIT
A -- Continue to next step.
3. CHECK CAN BUS WIRE FOR SHORT CIRCUIT (CAN MAIN BUS WIRE)




(a) Disconnect the CAN main bus wire connector (J27) from the wiring harness connector (CAN J/C1).




(b) Measure the resistance according to the value in the table below.
Standard resistance:






NG -- REPLACE WIRING HARNESS CONNECTOR (CAN J/C1)
OK -- Continue to next step.
4. CHECK CAN BUS WIRE FOR SHORT CIRCUIT (CAN MAIN BUS WIRE)
(a) Disconnect the CAN main bus wire connector (J43) from the wiring harness connector (CAN J/C2).




(b) Measure the resistance according to the value in the table below.
Standard resistance:





HINT: Confirm disconnection of the CAN main bus wire from the wiring harness connector (CAN J/C1) during measurement.

NG -- REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE WIRING HARNESS CONNECTOR (CAN J/C2)
5. CHECK CAN BUS WIRE FOR SHORT CIRCUIT
(a) Reconnect the connector for the short-circuited branch wire to the CAN J/C (the connector that caused the bus wire resistance to become normal (between 54 and 69 Ohms) when it was disconnected).
(b) Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the short-circuited branch wire is connected. CAN Communication System




(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH WIRE OR CONNECTOR
OK -- REPLACE CORRESPONDING ECU OR SENSOR