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
There may be a short circuit between the CAN bus lines when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ohms.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
* Turn the ignition switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
* Turn the ignition switch off before inspecting CAN bus wires for a ground short.
* After the ignition 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 ignition 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 ignition 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. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL
(a) Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and the branch wire.
CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
NOTICE:
When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.
NEXT -- Continue to next step.
2. CHECK FOR SHORT IN CAN BUS WIRES (DLC3 BRANCH WIRE)
(a) Disconnect the E86 CAN junction connector connector.
(b) 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 (CAN-H, CAN-L)
OK -- Continue to next step.
3. CHECK FOR SHORT IN CAN BUS WIRES (CAN JUNCTION CONNECTOR - YAW RATE SENSOR)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- CONNECT CONNECTOR
OK -- Continue to next step.
4. CHECK FOR SHORT IN CAN BUS WIRES (CAN JUNCTION CONNECTOR - STEERING ANGLE SENSOR)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- CONNECT CONNECTOR
OK -- Continue to next step.
5. CHECK FOR SHORT IN CAN BUS WIRES (CAN JUNCTION CONNECTOR - MASTER CYLINDER SOLENOID (SKID CONTROL ECU))
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- CONNECT CONNECTOR
OK -- Continue to next step.
6. CHECK FOR SHORT IN CAN BUS WIRES (CAN JUNCTION CONNECTOR - CENTER AIRBAG SENSOR ASSEMBLY)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- CONNECT CONNECTOR
OK -- Continue to next step.
7. CHECK FOR SHORT IN CAN BUS WIRES (CAN JUNCTION CONNECTOR - ECM)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- CONNECT CONNECTOR
OK -- Continue to next step.
8. CHECK FOR SHORT IN CAN BUS WIRES (CAN JUNCTION CONNECTOR - COMBINATION METER ECU)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- CONNECT CONNECTOR
OK -- REPLACE CAN JUNCTION CONNECTOR
9. CONNECT CONNECTOR
(a) Reconnect the E86 CAN junction connector connector.
NEXT -- Continue to next step.
10. CHECK FOR SHORT IN CAN BUS WIRES (YAW RATE SENSOR)
(a) Disconnect the E81 yaw rate sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE YAW RATE SENSOR Removal
11. CONNECT CONNECTOR
(a) Reconnect the E86 CAN junction connector connector.
NEXT -- Continue to next step.
12. CHECK FOR SHORT IN CAN BUS WIRES (STEERING ANGLE SENSOR)
(a) Disconnect the E16 steering angle sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE STEERING ANGLE SENSOR Removal
13. CONNECT CONNECTOR
(a) Reconnect the E86 CAN junction connector connector.
NEXT -- Continue to next step.
14. CHECK FOR SHORT IN CAN BUS WIRES (MASTER CYLINDER SOLENOID (SKID CONTROL ECU))
(a) Disconnect the A4 master cylinder solenoid (skid control ECU) connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Removal
15. CONNECT CONNECTOR
(a) Reconnect the E86 CAN junction connector connector.
NEXT -- Continue to next step.
16. CHECK FOR SHORT IN CAN BUS WIRES (CENTER AIRBAG SENSOR ASSEMBLY)
(a) Disconnect the E29 center airbag sensor assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE CENTER AIRBAG SENSOR ASSEMBLY Removal
17. CONNECT CONNECTOR
(a) Reconnect the E86 CAN junction connector connector.
NEXT -- Continue to next step.
18. CHECK FOR SHORT IN CAN BUS WIRES (ECM)
(a) Disconnect the E77 ECM connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE ECM Removal
19. CONNECT CONNECTOR
(a) Reconnect the E86 CAN junction connector connector.
NEXT -- Continue to next step.
20. CHECK FOR SHORT IN CAN BUS WIRES (COMBINATION METER ASSEMBLY (COMBINATION METER ECU))
(a) Disconnect the E14 combination meter assembly (combination meter ECU) connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE COMBINATION METER ASSEMBLY (COMBINATION METER ECU) Removal