How To Proceed With Troubleshooting

WARNING: This page is about a different car, the 2008 Toyota Yaris. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

DTCs for the CAN communication system are as follows: U0073, U0100, U0105, U0121, U0129 and B1499.
Refer to the troubleshooting section for each system if DTCs regarding the CAN communication system are not output.
Turn the ignition switch off before measuring the resistances of the CAN main wire and the CAN branch wire.
After the ignition switch is turned off, check that the key reminder warning system and light reminder warning system are not in operation.
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 doors need to be opened in order to check connectors, open the doors and leave them open.
HINT:

Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

CHECK CAN BUS LINE
1. Check the CAN bus line (See CAN BUS LINE ).
NEXT: GO TO NEXT STEP
CHECK INSTALLED SYSTEMS (ECUs AND SENSORS) THAT ADOPT CAN COMMUNICATION
NEXT: GO TO NEXT STEP
CHECK AND CLEAR DTCs
NEXT: GO TO NEXT STEP

CHECK CAN COMMUNICATION USING TECHSTREAM

Select "CAN Bus Check" (See DIAGNOSIS SYSTEM ).

Result

RESULT CHART

All ECUs and sensors connected to CAN communication system displayed on screen.	A
One ECU or sensor connected to CAN communication system not displayed on screen.	B
2 or more ECUs and sensors connected to CAN communication system not displayed on screen.	C

NOTE:

The systems (ECUs and sensors) that adopt CAN communication vary depending on the vehicle and option settings. Check which systems (ECUs and sensors) are installed on the vehicle (See DIAGNOSIS SYSTEM ).
Non-installed ECUs or sensors are not displayed. Do not mistake them for being in communication stop mode.
If two or more ECUs or sensors are not displayed on the Techstream, perform troubleshooting for open in one side of CAN bus line for each undisplayed ECU or sensor.

B: GO TO COMMUNICATION STOP MODE TABLE

C: GO TO OPEN IN ONE SIDE OF CAN BRANCH WIRE

A: GO TO NEXT STEP

DTC COMBINATION TABLE
1. Confirm trouble according to the combination of output DTCs regarding the CAN communication system.
  HINT:
  
  Previous CAN communication system DTCs may be the cause if CAN communication system DTCs are output and all ECUs and sensors connected to the CAN communication system are displayed on the Techstream "Communication Bus Check" screen.
NEXT: GO TO NEXT STEP
INSPECT CIRCUIT
NEXT: GO TO NEXT STEP
IDENTIFY PROBLEM
NEXT: GO TO NEXT STEP
REPAIR OR REPLACE
NEXT: GO TO NEXT STEP
PERFORM CONFIRMATION TEST