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Check CAN Bus Line for Short to +B





NETWORKING: CAN COMMUNICATION SYSTEM: Check CAN Bus Line for Short to +B
- Check CAN Bus Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus wires and +B when no resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of the DLC3.





* *1: w/ Manual (SOS) switch

* *2: for Navigation receiver type

* *3: for Radio and display type

WIRING DIAGRAM









INSPECTION PROCEDURE

NOTICE:
* Turn the power switch off before measuring the resistances between CAN main bus wires and between CAN main bus branch wires.
* Turn the power switch off before inspecting CAN bus wires for a ground short.
* After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
* Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the power switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

HINT
* Operating the power switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
* Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE

1. CHECK FOR SHORT TO +B IN CAN BUS WIRE (DLC3 BRANCH WIRE)

(a) Disconnect the cable from the negative (-) auxiliary battery terminal.

(b) Disconnect the DLC3 branch wire connector (L168) from the CAN No. 1 junction connector.





Text in Illustration





NOTICE:
* Before disconnecting the connector, make a note of where it is connected.
* Reconnect the connector to its original position.

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





Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE CAN MAIN BUS BRANCH WIRE CONNECTED TO DLC3
OK -- Continue to next step.

2. CHECK FOR SHORT TO +B IN CAN BUS WIRE

(a) Reconnect the DLC3 branch wire connector (L168) to the CAN No. 1 junction connector.

(b) Disconnect the connectors from the CAN No. 1 junction connector and CAN No. 2 junction connector one at a time.

HINT
Disconnect the ECU and sensor connectors other than the DLC3 branch wires and CAN main bus wires between the CAN No. 1 junction connector and CAN No. 2 junction connector.





Text in Illustration





(c) Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 16 (BAT), and between terminals 14 (CANL) and 16 (BAT) of the DLC3 each time a connector is disconnected.





Text in Illustration









Text in Illustration





Wiring Color









Text in Illustration





Wiring Color





*1: w/ Manual (SOS) switch

*2: for Navigation receiver type

*3: for Radio and display type

NOTICE:
Do not reconnect the disconnected connectors until this inspection is complete because there may be a short to +B in 2 or more CAN bus wires.

Result:





(d) When there is a short to +B in one or more of the bus wires that connect to an ECU (or sensor):

(1) Reconnect all of the connectors to the CAN junction connector, except for the one that was disconnected last (the bus wire that is shorted to +B). Check that the resistance shown on the tester is normal (6 kOhms or more) to confirm that there is a short to +B in the one bus wire only.

HINT
* Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus wires.
* Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

(e) When there is no short to +B in any of the bus wires that connect to the ECUs and sensors:

(1) With all the specified connectors for ECUs and sensors disconnected, proceed with the inspection of the CAN bus main wires between the CAN No. 1 junction connector and CAN No. 2 junction connector.

B -- CHECK FOR SHORT TO +B IN CAN BUS WIRE (ECU, SENSOR)
A -- Continue to next step.

3. CHECK FOR SHORT TO +B IN CAN BUS WIRE (CAN NO. 1 J/C)

(a) Disconnect the CAN main bus wire connector (L174) from the CAN No. 1 junction connector.





Text in Illustration





NOTICE:
* Before disconnecting the connector, make a note of where it is connected.
* Reconnect the connector to its original position.

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





Standard Resistance:





Text in Illustration





NG -- REPLACE CAN NO. 1 JUNCTION CONNECTOR
OK -- Continue to next step.

4. CHECK FOR SHORT TO +B IN CAN BUS WIRE (CAN NO. 1 J/C - CAN NO. 2 J/C)

(a) Reconnect the CAN main bus wire connector (L174) to the CAN No. 1 junction connector.

(b) Disconnect the CAN main bus wire connector (L180) from the CAN No. 2 junction connector.





Text in Illustration





NOTICE:
* Before disconnecting the connector, make a note of where it is connected.
* Reconnect the connector to its original position.

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





Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE CAN MAIN BUS WIRE (CAN NO. 1 J/C - CAN NO. 2 J/C)

OK -- REPLACE CAN NO. 2 JUNCTION CONNECTOR

5. CHECK FOR SHORT TO +B IN CAN BUS WIRE (ECU, SENSOR)

(a) Reconnect the connector of the bus wire that is shorted to +B to the CAN junction connector (the connector that caused the bus wire resistance to change to 6 kOhms or more when it was disconnected).

(b) Disconnect the connector that includes the DLC3 connected CAN wires (such as CANH and CANL) from the ECU (or sensor) to which the bus wire shorted to +B is connected CAN Communication System.

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





Standard Resistance:





Text in Illustration





HINT
If the resistance changes to 6 kOhms or higher when the connector is disconnected from the ECU (or sensor), there may be a short in the ECU (or sensor).

NG -- REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BUS WIRE OR CONNECTOR

OK -- REPLACE CORRESPONDING ECU OR SENSOR
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