Check CAN Bus Lines for Short Circuit

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

DESCRIPTION

There may be a short circuit between the V bus main lines and/or CAN branch lines when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ohms.

*1: for Navigation receiver type

*2: for Radio and display type

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:
* Before measuring the resistance of the CAN bus, turn the power switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
* After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work Service Precautions.
* Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output How to Proceed With Troubleshooting.
* After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.
* DTC check procedure: Turn the power switch on (IG), turn the cruise control system on using the cruise control switch (ON/OFF switch), wait at least 60 seconds, and then drive the vehicle at a speed of 50 km/h (31 mph) or more for at least 1.72 seconds.
* After the repair, perform CAN Bus Check and check that all the ECUs and sensors connected to the CAN communication system are displayed Diagnosis System.

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 IN CAN BUS LINES (ECM)

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

(b) Disconnect the ECM connector.

Text in Illustration

NG -- CHECK FOR SHORT IN CAN BUS LINES (METER CIRCUIT PLATE)

OK -- REPLACE ECM Removal

2. CHECK FOR SHORT IN CAN BUS LINES (METER CIRCUIT PLATE)

(a) Reconnect the ECM connector.

(b) Disconnect the meter circuit plate connector.

Text in Illustration

NG -- CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C)

OK -- REPLACE METER CIRCUIT PLATE Disassembly

3. CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C)

(a) Reconnect the meter circuit plate connector.

(b) Disconnect the wire harness connector from the CAN No. 2 junction connector (instrument panel connector holder left side).

Text in Illustration

Result:

B -- CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 1 J/C)

C -- CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 3 J/C)

D -- CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)
A -- Continue to next step.

4. CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C)

(a) Disconnect the wire harness connector from the CAN No. 2 junction connector (instrument panel connector holder right side).

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

Standard Resistance:

*1: for Navigation receiver type

*2: for Radio and display type

Text in Illustration

*1: for Navigation receiver type

*2: for Radio and display type

Result:

B -- CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)

C -- REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

A -- REPLACE CAN NO. 2 JUNCTION CONNECTOR

5. CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 1 J/C)

(a) Disconnect the wire harness connector from the CAN No. 1 junction connector (instrument panel wire side).

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

Standard Resistance:

Text in Illustration

Result:

B -- REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 2 J/C - CAN NO. 1 J/C)

C -- CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)
A -- Continue to next step.

6. CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 1 J/C)

(a) Disconnect the wire harness connector from the CAN No. 1 junction connector (engine room main wire side).

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

Standard Resistance:

Text in Illustration

Result:

B -- REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 1 J/C - ECM)

C -- CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)

A -- REPLACE CAN NO. 1 JUNCTION CONNECTOR

7. CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 3 J/C)

(a) Disconnect the wire harness connector from the CAN No. 3 junction connector (instrument panel wire side).

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

Standard Resistance:

Text in Illustration

Result:

B -- REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 2 J/C - CAN NO. 3 J/C)

C -- REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 3 J/C - METER CIRCUIT PLATE)

D -- CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)
A -- Continue to next step.

8. CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 3 J/C)

(a) Disconnect the wire harness connector from the CAN No. 3 junction connector (engine room main wire side).

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

Standard Resistance:

Text in Illustration

NG -- CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)

OK -- REPLACE CAN NO. 3 JUNCTION CONNECTOR

9. CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)

(a) Reconnect all wire harness connectors (CAN junction connector 1, CAN junction connector 2 and CAN junction connector 3).

(b) Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the short circuited branch line 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 becomes normal (between 54 and 69 Ohms) when the connector is disconnected from the ECU (or sensor), there may be a short in the ECU (or sensor).
* If the resistance does not become normal (between 54 and 69 Ohms) when the connector is disconnected from the ECU (or sensor), repair or replace the short circuited branch line or connector.

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

OK -- REPLACE CORRESPONDING ECU OR SENSOR