CAN COMMUNICATION SYSTEM HOW TO PROCEED WITH TROUBLESHOOTING

  1. PRECAUTIONS WHEN TROUBLESHOOTING

    Note

    • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

    • If the CAN communication system is malfunctioning, check the contact pressure of the terminals in connectors, as insufficient terminal contact pressure may be the cause Click here.

    • Refer to Diagnosis System for the DTCs for the CAN communication system.

    • Refer to troubleshooting of each system if DTCs regarding the CAN communication system are not output.

    • Before measuring the resistance of the CAN bus, turn the power switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

    • After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work Click here.

    1. CAN communication DTCs are output for CAN main bus and CAN branch malfunctions as well as for internal malfunctions or power source malfunctions of ECUs or sensors for systems using CAN communication. Therefore, when DTCs for internal malfunctions or power source malfunctions of corresponding systems are output at the same time as CAN communication DTCs, troubleshoot according to the internal malfunction and power source malfunction DTCs.

    2. The DLC3 branch and V bus main bus circuits can be checked for malfunctions by inspecting at the DLC3 terminals using a electrical tester.

      Note

      • When inspecting at the DLC3 connector, do not connect the tester directly to the terminals. Instead, connect using service wires.

      • Inspections for an open in an ECU or sensor branch, or inspections for buses other than the V bus cannot be performed from the DLC3.

    3. An open in a branch for ECUs or sensors that are connected to the CAN main bus can be checked by performing a CAN bus check using the Techstream. (This inspection is possible when the DLC3 branch and V bus main bus lines are normal.)

    4. If the V bus had a communication error, the probable ECU or sensor for which communication stopped can be determined using the combination of communication DTCs (DTCs that start with U) that are output.

    5. A malfunction of sub bus 15 can be determined based on the number of DTCs stored by the ECM, power management control ECU and brake booster with master cylinder assembly (skid control ECU).

    6. If a sub bus has a communication error, the gateway function equipped ECU (sub bus monitor ECU) detects it and stores DTCs related to the error.

      Tech Tips

      On the Techstream, gateway function equipped ECUs display DTCs for ECUs connected to the sub bus.

    7. When an open circuit is detected, before disconnecting related connectors for inspection, push in on the connector body to check that the connector is not loose or disconnected.

    8. When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

    1. VEHICLE BROUGHT TO WORKSHOP

      Tech Tips

      • If the power switch can be turned on (IG) (the power source mode can be changed to on (IG)) when the vehicle is brought in for repair, check for DTCs and check the illumination condition of the indicators in the combination meter assembly and the basic operation of the vehicle (such as steering operation) promptly.

      • Do not turn the power switch off until the inspection of the vehicle is finished, as some fail-safe functions are canceled when the power switch is turned off.

      • If the power switch cannot be turned on (IG) (the power source mode cannot be changed to on (IG)) when the vehicle is brought in, measure the voltage of the auxiliary battery. If the voltage is below 11 V, recharge or replace the auxiliary battery before performing troubleshooting.

      • If the power switch cannot be turned on (IG) even though the auxiliary battery voltage is normal, repair this malfunction before performing troubleshooting Click here.

      NEXT

    2. CUSTOMER PROBLEM ANALYSIS

      Tech Tips

      • When troubleshooting, confirm that the problem symptoms have been accurately identified. Preconceptions should be discarded in order to make an accurate judgment. To clearly understand what the problem symptoms are, it is extremely important to ask the customer about the problem and the conditions at the time the malfunction occurred.

      • Ask the customer if the vehicle is/was equipped with additional devices such as a theft deterrent device or monitor. (If equipped, explain the customer that the additional devices will be removed before performing troubleshooting as the malfunction cannot be checked properly.)

      1. It is useful to confirm the symptoms and the conditions in which the vehicle was operating at the time when a malfunction occurred. This helps to narrow down the malfunctioning part.

        Tech Tips

        • What was affected (system, part or meter warning indicators)

        • What happened (details of the malfunction)

        • When (occurrence date and time, frequency and if it recurs or not)

        • Under what kind of situation did the problem occur (driving and operating condition at the occurrence and weather)

        • Road type or condition (city, suburb, paved road, unpaved road, highway, etc.)

        • Return conditions (what made the vehicle return to normal. Example: power switch was turned off)

          Points to be confirmed
          Symptom

          • Electric power steering

            - Normal

            - A little heavier than usual

            - There was no assist

          • Air conditioning

            - Whether the air conditioning system operated

            - Whether the blower fan operated

          • Multi-information display items

            - Whether the update of multi-information display items stopped

            - Whether the numeric part of drivable distance was not displayed

          • Door inside handle illumination

            - Whether the door inside handle illumination was dimmed when the shift lever was in a position other than P

          • Auto lock and unlock operation

            - Whether the speed linked auto-lock function operated while driving

            - Whether the unlock function operated when the shift lever was moved to P

          • Wireless door lock function and smart entry function

            - Whether the lock/unlock function operated

            - Whether the illumination was turned on when the key was brought into a smart detection area

          • Operation of other systems of concern
          Meter warning lights

          • Illumination of warning lights and the order in which they illuminated

            - HV system warning light

            - Check engine (MIL)

            - ABS

            - SRS

            - EPS

            - SLIP

            - Master

            - Brake

            - Cruise (amber)

            - Others

          • Needle movement

            - Speedometer

            - Coolant temperature gauge

            - Hybrid system indicator

          • Content displayed on the multi-information display
        NEXT

    3. CHECK TECHSTREAM OPERATION

      Tech Tips

      Read the Techstream operators manual before use Click here.

      1. Connect the Techstream to the DLC3.

      2. Turn the power switch on (IG).

      3. Turn the Techstream on.

      4. Check that the Techstream and ECUs can communicate with the power switch on (IG).

        Tech Tips

        • If communication is impossible, the Techstream screen will indicate an error.

        • If communication between the Techstream and ECUs is impossible, either the Techstream or vehicle has a malfunction.

        • When communication between the Techstream and the vehicle is impossible, but communication is possible when the Techstream is connected to another vehicle, the vehicle is malfunctioning. Inspect the CANH and CANL branch lines of the DLC3 and the ECU power source circuits (in this case perform steps 7 to 9 first). In addition, check that the BAT terminal of the DLC3 receives auxiliary battery voltage (11 V or more).

        • If communication between the Techstream and ECUs is still impossible even when the Techstream is connected to another vehicle, the Techstream has the malfunction. Perform the self tests described in the Techstream operators manual. (The Techstream may be malfunctioning or its battery may be discharged.)

        Result Proceed to
        OK (Communication between the Techstream and the vehicle is possible.) A
        OK (Communication between the Techstream and the vehicle is impossible but communication is possible when connected to another vehicle.) B
        NG (Communication is not possible between the Techstream and the vehicle, or between the Techstream and another vehicle.) C
        B

        Go to step 7
        C

        Refer to Techstream operator's manual
        A

    4. CHECK DTC

      1. Using the Techstream, perform Health Check to read current and history DTCs and record them.

        Note

        • CAN communication DTCs are output when there is an open or short in any of the communication lines. Any problems with the power source of a corresponding ECU or sensor, or problems in the ECU, the sensor itself also cause these DTCs to be output.

        • If a CAN communication line connector is disconnected with the power switch on (IG), the ECUs of the corresponding system and related systems store a DTC.

        Tech Tips

        • If an open in a CAN main bus line, a short between the CAN bus lines (CANH and CANL) or a +B or ground short in a CAN bus occurs, DTCs of almost all ECUs and sensors on the CAN bus may be output (or a message indicating a communication error may be displayed on the Techstream screen). In this case, check the resistance of the CAN bus (steps 7 to 9) first.

        • If an open occurs in just one of the lines of a CAN branch, DTCs which are not related to malfunctioning parts may be output (DTCs may be displayed randomly), or a message indicating a communication error may be displayed on the Techstream.

      2. Read the freeze frame data using the Techstream and record it.

        NEXT

    5. CHECK COMMUNICATION MALFUNCTION CHECK (CONNECTION STATUS CHECK USING TECHSTREAM)

      1. Select "Communication Malfunction Check" from the screen on the Techstream.

      2. Record all the DTCs stored for ECUs and sensors.

        NEXT

    6. CHECK CAN BUS CHECK (CONNECTION STATUS CHECK USING TECHSTREAM)

      1. Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Click here.

      2. Select "CAN Bus Check" from the screen on the Techstream.

      3. Observe the screen for approximately 2 minutes to check the ECUs and sensors displayed on the screen.

        NEXT

    7. CHECK DLC3 BRANCH LINE AND V BUS MAIN LINE (CANH - CANL)

      Note

      Before measuring the resistance of the CAN bus, turn the power switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

      Tech Tips

      Operating the power 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.

      1. Disconnect the cable from the negative (-) auxiliary battery terminal.

        A011W30E43

      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance
        Tester Connection Condition Specified Condition
        I39-6 (CANH) - I39-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω
        Text in Illustration
        *1 DLC3
        Result
        Result Proceed to
        OK A
        NG (70 Ω or higher) B
        NG (Below 54 Ω) C
        B

        GO TO OPEN IN CAN MAIN BUS LINE Click here

        C

        GO TO SHORT IN CAN BUS LINES Click here

        A

    8. CHECK FOR SHORT TO GND IN V BUS (CANH, CANL - CG)

      1. Measure the resistance according to the value(s) in the table below.

        A011W30E44
        Standard Resistance
        Tester Connection Condition Specified Condition
        I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
        I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
        Text in Illustration
        *1 DLC3
        NG

        GO TO SHORT TO GND IN CAN BUS LINE Click here

        OK

    9. CHECK FOR SHORT TO +B IN V BUS (CANH, CANL - BAT)

      1. Measure the resistance according to the value(s) in the table below.

        A011W30E45
        Standard Resistance
        Tester Connection Condition Specified Condition
        I39-6 (CANH) - I39-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
        I39-14 (CANL) - I39-16 (BAT) Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher
        Text in Illustration
        *1 DLC3
        NG

        GO TO SHORT TO +B IN CAN BUS LINE Click here

        OK

    10. CHECK RESULT OF CAN BUS CHECK (CONNECTION STATUS CHECK USING TECHSTREAM)

      1. Inspect or repair the probable malfunctioning part based on the check result of step 6 (the step in which CAN Bus Check was performed).

        Result of CAN Bus Check (Connection Status Check Using Techstream)
        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

        • All ECUs except the power management control ECU connected to sub bus 11 are not displayed on the screen.

        • The power management control ECU (PM1 Gateway) outputs DTC U1002.

        (Open or short in sub bus 11 main lines.)

        		 B

        When the V bus is selected using the drop down list, all the ECUs and sensors connected to the V bus are displayed on the screen, but when sub bus 15 is selected, no connected ECUs or sensors are displayed.

        (Open or short in sub bus 15 main lines.)

        		 C

        All ECUs connected to sub bus 11 are not displayed on the screen.

        (Open in power management control ECU branch lines or power management control ECU malfunction.)

        		 D

        No ECUs or sensors connected to the ECM or sub bus 15 are displayed on the screen.

        (Open in ECM main lines or ECM malfunction.)

        		 E

        One of the ECUs and sensors connected to the V Bus is not displayed on the screen.

        (Open in ECU or sensor branch lines, or communication is interrupted.)

        		 F

        • One of the ECUs and sensors connected to sub bus 11 is not displayed on the screen.*

          (Open in ECU or sensor branch lines, or communication is interrupted.)

        • One of the ECUs and sensors connected to sub bus 15 is not displayed on the screen.

          (Open in ECU or sensor branch lines, or communication is interrupted.)

        		 G

        In addition to ECUs and sensors which are connected to the CAN communication system but are not displayed on the screen, there are ECUs or sensors for which the detection status changes (changes between detected and not detected) during the inspection.

        (Open in one side of ECU or sensor branch lines.)

        		 H

        Note

        • *: In this case, as the power management control ECU (PM1 Gateway) outputs communication DTCs (DTCs that start with U), the problem area can be determined from those DTCs.

        • Non-installed ECUs or sensors will not be displayed. Do not mistake them for being in communication stop mode.

        • It may be possible to select buses that do not have ECUs or sensors from the bus selection pull-down menu on the Techstream. This is not a malfunction. (This occurs when optional devices are not on a sub bus that is monitored by a gateway function equipped ECU.)

        Tech Tips

        • Regarding CAN Bus Check, refer to How to Interpret CAN Bus Diagnosis (CAN Bus Check) Screen Click here.

        • If the detection status of ECUs changes during the inspection, one of the branch lines of a connected ECU or sensor may be open. (Signals from the ECU or sensor that has an open in one of its branch lines create electrical noise, affecting response to the Techstream and whether or not the ECUs and sensors are displayed.)

        • Regarding the ECUs connected to sub bus 11, the power management control ECU displays communicating ECUs on the Techstream. If the communication between the power management control ECU and an ECU stops for 3 seconds or more, the ECU will no longer be displayed on the Techstream.

        • Regarding the ECUs connected to sub bus 15, the ECM displays communicating ECUs on the Techstream. If the communication between the ECM and an ECU stops for 3 seconds or more, the ECU will no longer be displayed on the Techstream.

        • Regarding the communication stop mode for ECUs connected to sub bus 11, refer to the inspection procedure for the DTCs that indicate a communication stop.

        B

        GO TO U1002 Click here

        C

        GO TO U0100, U0129, U0293 Click here

        D

        GO TO POWER MANAGEMENT CONTROL ECU COMMUNICATION STOP MODE Click here

        E

        GO TO ECM COMMUNICATION STOP MODE Click here

        F

        GO TO COMMUNICATION STOP MODE TABLE Click here

        G

        GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

        H

        GO TO OPEN IN ONE SIDE OF CAN BRANCH LINE Click here

        A

    11. CHECK RESULT OF COMMUNICATION MALFUNCTION CHECK (SELECT THE MALFUNCTIONING BUS)

      1. Inspect or repair the probable malfunctioning part based on the check result of step 5 (the step in which checking for communication malfunction DTCs was performed).

        Check Result of Communication Malfunction Check (Select Malfunctioning Bus)
        Result Proceed to

        • The sub bus monitor ECU has not output communication DTCs but ECUs connected to the V bus have stored communication DTCs.

          (A malfunction occurred in the V Bus.)

        • ECUs connected to sub bus 15 have not output communication DTCs but ECUs connected to the V bus have stored communication DTCs.

          (A malfunction occurred in the V Bus.)

          • The ECM has not output DTC U0293 (Lost Communication with HV ECU).

          • The power management control ECU has not output DTC U0100 (Lost Communication with ECM/PCM "A") or DTC U0129 (Lost Communication with Brake System Control Module (U0129)).

          • The brake booster with master cylinder assembly (skid control ECU) has not output DTC U0293 (Lost Communication with HV ECU)

        		 A

        The power management control ECU (PM1 Gateway) outputs DTC U1002.

        (A malfunction occurred in sub bus 11.)

        		 B

        ECUs connected to sub bus 15 store communication error DTCs.

        (A malfunction occurred in sub bus 15.)

        • The ECM outputs only DTC U0293 (Lost Communication with HV ECU).

        • The power management control ECU outputs only DTC U0100 (Lost Communication with ECM/PCM "A") and DTC U0129 (Lost Communication with Brake System Control Module).

        • The brake booster with master cylinder assembly (skid control ECU) outputs only DTC U0293 (Lost Communication with HV ECU).

        		 C

        The power management control ECU (PM1 Gateway) outputs DTCs other than DTC U1002.

        (A malfunction occurred in an ECU branch line connected to sub bus 11.)

        		 D

        The power management control ECU outputs only DTC U0129 (Lost Communication with Brake System Control Module).

        (A malfunction occurred in an ECU branch line connected to sub bus 15.)

        		 E

        Tech Tips

        • Only sub bus 11 has a sub bus monitor ECU.

        • The term ''sub bus monitor ECU'' refers to a gateway function equipped ECU that is able to monitor a bus and store DTCs.

        • When checking for communication DTCs, refer to How to Interpret Communication DTCs (DTCs that start with U) Click here.

        • Because a gateway function equipped ECU (sub bus monitor ECU) monitors signals from all ECUs that are connected to its sub bus, a gateway function equipped ECU can detect ECUs with a communication stop more accurately. In this case, perform troubleshooting by referring to the DTC combination table for the sub bus Click here.

        • If communication DTCs are stored, and all ECUs and sensors connected to the CAN communication system are displayed on the Communication Bus Check (CAN bus check) screen of the Techstream, a past malfunction that is currently not occurring is suspected.

        • When a CAN branch of the V bus is malfunctioning, because the ECUs and sensors related to it detect the malfunction, the problem area can be determined using the combination of DTCs that are output.

        • When sub bus 11 is malfunctioning, the power management control ECU detects a communication stop for connected ECUs and a network communication error, and stores DTCs.

        • On the Techstream, the PM1 Gateway item displays the DTCs for ECUs connected to sub bus 11.

        • When both the sub bus monitor ECU and the ECUs connected to the V bus store communication DTCs, check and repair the corresponding sub bus first.

        B

        GO TO U1002 Click here

        C

        GO TO U0100, U0129, U0293 Click here

        D

        GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

        E

        GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

        A

    12. DTC COMBINATION TABLE

      1. Confirm the problem according to the combination of output DTCs regarding the CAN communication system Click here.

        Result Proceed to
        Combination of DTCs is not in DTC Combination Table A
        Combination of DTCs is in DTC Combination Table B

        Tech Tips

        CAN communication system history DTCs may indicate the problem if CAN communication system DTCs are output and all ECUs and sensors connected to the CAN communication system are displayed on "CAN Bus Check" of the Techstream.

        B

        GO TO COMMUNICATION STOP MODE TABLE Click here

        A

    13. IDENTIFICATION OF PROBLEM (PAST MALFUNCTION IN MAIN BUS OF V BUS)

      1. Connect the cable to the negative (-) auxiliary battery terminal.

      2. Clear the DTCs using the Techstream.

      3. Perform the tests in Symptom Simulation to check the wire harnesses and connectors including those for V bus main bus lines Click here.

      4. Based on the results of the check, inspect the parts that output DTCs to determine the malfunctioning part.

        Tech Tips

        If DTCs are output, do not turn the power switch off.

        NEXT

    14. REPAIR OR REPLACEMENT

      NEXT

    15. CONFIRMATION TEST

      NEXT
      END