Part 1

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 in the CAN bus main wire and/or CAN branch wire when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ohms.

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:
* Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN 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 IN CAN BUS WIRES (CAN NO. 1 J/C - CAN NO. 2 J/C)

(a) Turn the power switch off.

(b) Disconnect the CAN No. 1 junction connector.

Text in Illustration

NG -- CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 2 J/C - CAN NO. 1 J/C)
OK -- Continue to next step.

2. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - COMBINATION METER)

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

Standard Resistance:

Text in Illustration

NG -- CHECK FOR SHORT IN CAN BUS WIRES (COMBINATION METER)
OK -- Continue to next step.

3. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - DLC3)

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

Standard Resistance:

Text in Illustration

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

4. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - SKID CONTROL ECU)

(a) Disconnect the skid control ECU (brake booster with master cylinder) connector.

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (CAN NO. 1 J/C - SKID CONTROL ECU)
OK -- Continue to next step.

5. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - NAVIGATION ECU)

HINT
For vehicles without the navigation system, go to the next step.

(a) Disconnect the navigation ECU connector.

Text in Illustration

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (CAN NO. 1 J/C - NAVIGATION ECU)
OK -- Continue to next step.

6. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - STEERING ANGLE SENSOR)

(a) Disconnect the steering angle sensor connector.

Text in Illustration

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (CAN NO. 1 J/C - STEERING ANGLE SENSOR)
OK -- Continue to next step.

7. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - POWER STEERING ECU)

(a) Disconnect the power steering ECU connector.

Text in Illustration

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (CAN NO. 1 J/C - POWER STEERING ECU)
OK -- Continue to next step.

8. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - YAW RATE SENSOR)

(a) Disconnect the yaw rate sensor connector.

Text in Illustration

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (CAN NO. 1 J/C - YAW RATE SENSOR)
OK -- Continue to next step.

9. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - CERTIFICATION ECU)

(a) Disconnect the certification ECU connector.

Text in Illustration

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (CAN NO. 1 J/C - CERTIFICATION ECU)
OK -- Continue to next step.

10. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C - MAIN BODY ECU)

(a) Disconnect the main body ECU connector.

Text in Illustration

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (CAN NO. 1 J/C - MAIN BODY ECU)
OK -- Continue to next step.

11. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C)

(a) Reconnect the CAN No. 1 junction connector.

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

Standard Resistance:

Text in Illustration

NOTICE:
* The resistance must be measured after the main wire connected ECUs (ECM and combination meter), CAN No. 1 junction connector and No. 2 junction connector are reconnected.
* The resistance must be measured after the CAN No. 1 junction connector branch wire connected ECU and sensor connectors are disconnected.

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

12. CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR)

(a) Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.

Text in Illustration

(b) While observing the resistance value shown on the ohmmeter, reconnect each ECU and sensor connector until the resistance becomes abnormal (Below 54 Ohms).

HINT
If the resistance becomes abnormal when an ECU connector is reconnected, there may be a short in the ECU.

NEXT -- REPLACE CORRESPONDING ECU OR SENSOR