LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2008 >> Matrix Base, Standard >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Can Communication System >> How To Proceed With Troubleshooting
April 5, 2026: LEMON Manuals is launched! Read the announcement.

How To Proceed With Troubleshooting

  1. INSPECT BATTERY VOLTAGE 

    Standard voltage: 11 - 14 V 

    HINT:

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

  2. CHECK AND CLEAR DTCS 
    NOTE: DTCs for the CAN communication system are as follows: U0073, U0123, U0124 and U0126.

    HINT:

    • CAN communication DTCs are output 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 cause these DTCs to be output.
    • If a CAN communication wire connector is disconnected with the ignition switch ON, the ECUs of the corresponding system and related systems record a DTC.
  3. CHECK FOR INSTALLED SYSTEMS (ECUS & SENSORS) THAT ADOPT CAN COMMUNICATION 
    1. Check the adopted brake control system.
  4. CHECK DLC3 BRANCH WIRE AND CAN NO. 1 BUS CIRCUIT MAIN WIRE (CANH - CANL) 
    NOTE: Turn the ignition switch off before measuring the resistances of the CAN main wire and the CAN branch wire.
    1. Turn the ignition switch off.
    2. Measure the resistance according to the value(s) in the table below.
      Fig 1: Identifying Terminal CANH And CANL Of DLC3 Connector
      G05576474Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard resistance 

      STANDARD RESISTANCE SPECIFIED CONDITIONS

      Tester Connection Condition Specified Condition
      D1-6 (CANH) - D1-14 (CANL) Ignition switch off 54 to 69 Ω

      Result (w/VSC) 

      RESULT CHART (W/VSC)

      Result Proceed to
      54 to 69 Ω A
      70 Ω or higher B
      Below 53 Ω C

      Result (w/o VSC) 

      RESULT CHART (W/O VSC)

      Result Proceed to
      OK A
      NG D

    B: Go TO CAN MAIN WIRE FOR DISCONNECTION (See  OPEN IN CAN MAIN BUS LINE   ) 

    C: Go TO CHECK CAN BUS LINES FOR SHORT CIRCUIT  (See SHORT IN CAN BUS LINES  )

    D: Go TO  "ECM COMMUNICATION STOP MODE "

    A: Go to next step 

  5. CHECK FOR SHORT TO GND IN CAN BUS (CANH, CANL - CG) 
    Fig 2: Identifying Terminals CANH, CANL And CG Of DLC3 Connector
    G05576475Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFIED CONDITIONS

      Tester Connection Condition Specified Condition
      D1-6 (CANH)-D1-4 (CG) Ignition switch off 200 Ω or higher
      D1-14 (CANL)-D1-4 (CG) Ignition switch off 200 Ω or higher

      Result 

      RESULT CHART

      Result Proceed to
      OK A
      NG (w/VSC) B
      NG (w/o VSC) C

    B: Go TO CHECK CAN BUS LINE FOR SHORT TO GND  (See SHORT TO GND IN CAN BUS LINE  )

    C: Go TO  "ECM COMMUNICATION STOP MODE "

    A: Go to next step 

  6. CHECK FOR SHORT TO +B IN CAN BUS (CANH, CANL - BAT) 
    1. Measure the resistance according to the value(s) in the table below.
      Fig 3: Identifying Terminal DLC3 Connector
      G05576476Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard resistance 

      STANDARD RESISTANCE SPECIFIED CONDITIONS

      Tester Connection Condition Specified Condition
      D1-6 (CANH)-D1-16 (BAT) Negative battery terminal disconnected 6 kΩ or higher
      D1-14 (CANL)-D1-16 (BAT) Negative battery terminal disconnected 6 kΩ or higher

      Result 

      RESULT CHART

      Result Proceed to
      OK A
      NG (w/VSC) B
      NG (w/o VSC) C

    B: Go TO CHECK CAN BUS LINE FOR SHORT TO +B  (See SHORT TO B+ IN CAN BUS LINE  )

    C: Go TO  "ECM COMMUNICATION STOP MODE "

    A: Go to next step 

  7. CHECK WITH TECHSTREAM 
    1. Using Techstream, check for ECUs and sensors connected to CAN bus (See DIAGNOSIS SYSTEM  ).
    2. Observe the screen for approximately 1 minute to check the ECUs and sensors displayed on the screen.

      Result 

      RESULT CHART

      Result Proceed to
      w/VSC 
      All ECUs and sensors connected to the CAN communication system are displayed on the screen. (CAN bus circuit is currently normal)      		 A
      w/VSC 
      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
      w/VSC 
      Some of the ECUs and sensors connected to the CAN communication system are not displayed on the screen. During this check, some ECUs and sensors repeatedly appear and disappear from the screen.
      (Open in one side of ECU or sensor branch wires)      		 C
      w/o VSC 
      The ECM is not displayed on the screen.      		 D
      NOTE: Non-installed ECUs or sensors will not be displayed. Do not mistake them for being in the communication stop mode.

      HINT:

      The ECUs and sensors that repeatedly appear and disappear from the screen during this check are considered normal. (The response to Techstream and the tester display are 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 CHART "

    C: Go TO  "OPEN IN ONE SIDE OF CAN BRANCH WIRE "

    D: Go TO  "ECM COMMUNICATION STOP MODE " .

    A: Go to next step 

  8. DTC COMBINATION TABLE 
    1. Confirm trouble according to the combination of output DTCs regarding the CAN communication system (See DIAGNOSIS SYSTEM  ).
  9. CIRCUIT INSPECTION 
  10. IDENTIFICATION OF PROBLEM 
  11. REPAIR OR REPLACE 
  12. CONFIRMATION TEST 

    NEXT : END 

scientia non olet · About LEMON Manuals