Open in One Side of CAN Branch Line
CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: Open in One Side of CAN Branch Line
- Open in One Side of CAN Branch Line
DESCRIPTION
If 2 or more ECUs and/or sensors do not appear on the Techstream "CAN Bus Check" screen, one side of the CAN branch wire may be open (One side of the CANH [branch wire]/CANL [branch wire] of the ECU and/or sensor is open).
WIRING DIAGRAM
INSPECTION PROCEDURE
CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.
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, first disconnect the cable from the negative battery terminal and confirm that the alarm function is no longer operating. Then, 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.
* When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.
HINT
* Perform the following inspection for the ECUs (sensors) which are not displayed on the Techstream. If a malfunction cannot be identified, perform the following inspections for the ECUs (sensors) connected to the CAN communication system.
* Do not remove the center airbag sensor assembly and ECM, as they are the end parts of the circuit. If removed, CAN communication will not be possible.
* The open circuit confirmation of the center airbag sensor assembly, ECM and main wire is performed in the Check CAN Bus Line procedure of How to Proceed with Troubleshooting. This inspection only has procedures for checking for an open circuit on one side of the CAN branch wire.
PROCEDURE
1. CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (YAW RATE SENSOR)
(a) Disconnect the E81 yaw rate sensor connector.
(b) Select "CAN Bus Check" on the Techstream Diagnosis System.
Result
B -- CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (MASTER CYLINDER SOLENOID (SKID CONTROL ECU))
A -- Continue to next step.
2. CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (YAW RATE SENSOR BRANCH WIRE)
(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 OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE YAW RATE SENSOR Removal
3. CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (MASTER CYLINDER SOLENOID (SKID CONTROL ECU))
(a) Disconnect the A4 master cylinder solenoid (skid control ECU) connector.
(b) Select "CAN Bus Check" on the Techstream Diagnosis System.
Result
B -- CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (CENTER AIRBAG SENSOR ASSEMBLY)
A -- Continue to next step.
4. CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (MASTER CYLINDER SOLENOID (SKID CONTROL ECU) BRANCH WIRE)
(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 OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Removal
5. CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (CENTER AIRBAG SENSOR ASSEMBLY)
(a) Disconnect the E29 center airbag sensor assembly connector.
(b) Select "CAN Bus Check" on the Techstream Diagnosis System.
Result
B -- CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (STEERING ANGLE SENSOR BRANCH WIRE)
A -- Continue to next step.
6. CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (CENTER AIRBAG SENSOR ASSEMBLY BRANCH WIRE)
(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 OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE CENTER AIRBAG SENSOR ASSEMBLY Removal
7. CHECK FOR OPEN IN ONE SIDE OF BRANCH WIRE (STEERING ANGLE SENSOR BRANCH WIRE)
(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 OR CONNECTOR (CAN-H, CAN-L)
OK -- REPLACE STEERING ANGLE SENSOR Removal