How To Proceed With Troubleshooting

HINT: 

*: Use the Techstream

1. INSPECT BATTERY VOLTAGE 

   Standard voltage

   11 to 14 V

   HINT: 

   If the voltage is below 11 V, recharge or replace the battery before proceeding to the next step.

   NEXT: Go to next step 

2. CHECK AND CLEAR DTCs* 

   HINT: 

   • CAN communication DTCs are stored when there is an open or short in any of the communication wires. Any problems with the power source of a corresponding ECU or sensor, or problems in the ECU or the sensor itself also can cause these DTCs to be stored.
   • If a CAN communication wire connector is disconnected with the engine switch on (IG), the ECUs of the corresponding system and related systems store a DTC.

   NEXT: Go to next step 

3. CHECK DLC3 BRANCH WIRE AND CAN BUS CIRCUIT MAIN WIRE (CANH - CANL) 
   NOTE:

   • Turn the engine switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
   • Turn the engine switch off before inspecting CAN bus wires for a ground short.
   • After the engine 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 engine 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 engine 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.
   1. Turn the engine switch off.
   2. Measure the resistance according to the value(s) in the table below.
      Fig 1: J21 Connector Terminal Identification

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      STANDARD RESISTANCE
      
      

      Tester Connection	Condition	Specified Value	Proceed to
      J21-6 (CANH) - J21-14 (CANL)	Engine switch off	54 to 69 Ω	A
      J21-6 (CANH) - J21-14 (CANL)	Engine switch off	70 Ω or higher	B
      J21-6 (CANH) - J21-14 (CANL)	Engine switch off	Below 54 Ω	C

      TEXT IN ILLUSTRATION
      
      

      *1

      DLC3

      B → GO TO OPEN IN CAN MAIN LINE. Refer to  Open in CAN Main Bus Line  

      C → GO TO CHECK CAN BUS LINES FOR SHORT CIRCUIT. Refer to  Check CAN Bus Lines for Short Circuit  

      A: Go to next step 

4. CHECK FOR SHORT TO GND IN CAN BUS (CANH, CANL - CG) 
   1. Turn the engine switch off.
   2. Measure the resistance according to the value(s) in the table below.
      Fig 2: J21 Connector Terminal Identification

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      STANDARD RESISTANCE
      
      

      Tester Connection	Condition	Specified Value
      J21-6 (CANH) - J21-4 (CG)	Engine switch off	200 Ω or more
      J21-14 (CANL) - J21-4 (CG)	Engine switch off	200 Ω or more

      TEXT IN ILLUSTRATION
      
      

      *1

      DLC3

      NG → GO TO CHECK CAN BUS LINE FOR SHORT TO GND. Refer to  Check CAN Bus Line for Short to GND  

      OK: Go to next step 

5. CHECK FOR SHORT TO +B IN CAN BUS (CANH, CANL - BAT) 
   1. Disconnect the cable from the negative (-) battery terminal.
   2. Measure the resistance according to the value(s) in the table below.
      Fig 3: J21 Connector Terminal Identification

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      STANDARD RESISTANCE
      
      

      Tester Connection	Condition	Specified Value
      J21-6 (CANH) - J21-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or more
      J21-14 (CANL) - J21-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or more

      TEXT IN ILLUSTRATION
      
      

      *1

      DLC3

      NG → GO TO CHECK CAN BUS LINE FOR SHORT TO +B. Refer to  Check CAN Bus Line for Short to +B  

      OK: Go to next step 

6. CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION 
   1. Based on the vehicle equipment and specifications, confirm the systems that use CAN communication. Refer to DIAGNOSIS SYSTEM .

      NEXT: Go to next step 

7. CHECK ECUS CONNECTED TO CAN BUS* 
   1. Using the Techstream, select "CAN Bus Check" from the "System Select".
   2. Observe the screen for approximately 1 minute to check the ECUs and sensors displayed on the screen.
      RESULT
      
      

      Result	Proceed to
      All ECUs and sensors connected to the CAN communication system are displayed on the screen. (CAN bus circuit is currently normal.)	A
      One of the ECUs and sensors connected to the CAN communication system is not displayed on the screen. (Open in ECU or sensor branch wires, or communication interrupted.)	B
      Some ECUs and sensors repeatedly appear and disappear from the screen during this check. (Open in one side of ECU or sensor branch wires.)	C

      NOTE:

      • The systems (ECUs and sensors) that adopt CAN communication vary depending on the vehicle and optional equipment. Check which systems (ECUs and sensors) are installed on the vehicle.
      • Non-installed ECUs or sensors are not displayed. Do not mistake them for being in communication stop mode.
      • Techstream display is affected by signals output from other ECUs which have an open circuit in either of their CAN branch wires.

      B → GO TO COMMUNICATION STOP MODE TABLE. Refer to  PROBLEM SYMPTOMS TABLE  

      C → GO TO OPEN IN ONE SIDE OF CAN BRANCH LINE. Refer to  Open in One Side of CAN Branch Line  

      A: Go to next step 

8. DTC COMBINATION TABLE 
   1. Confirm trouble according to the combination of output DTCs regarding the CAN communication system. Refer to DIAGNOSIS SYSTEM .

      HINT: 

      • Sometimes CAN communication system DTCs are output, but all the ECUs and sensors connected to the CAN communication system are displayed on the Techstream. In this case, previous or history DTCs may indicate the cause of the problem.
      • ECUs related to a problem in the CAN bus will store DTCs to indicate communication malfunctions. Communication stop mode in the CAN bus can be determined by comparing the combination of DTCs that have been set. Refer to the DTC combination table for the CAN bus.

      NEXT: Go to next step 

9. CIRCUIT INSPECTION 

   NEXT: Go to next step 

10. IDENTIFICATION OF PROBLEM 

    NEXT: Go to next step 

11. REPAIR OR REPLACE 

    NEXT: Go to next step 

12. CONFIRMATION TEST 

    NEXT → END