NETWORKING: CAN COMMUNICATION SYSTEM (for Gasoline Model): HOW TO PROCEED WITH TROUBLESHOOTING; 2019 - 2022 MY Avalon [04/2018 - ]

Last Modified: 08-21-2023	6.11:8.1.0	Doc ID: RM100000001AN9V
Model Year Start: 2019	Model: Avalon	Prod Date Range: [04/2018 - ]
Title: NETWORKING: CAN COMMUNICATION SYSTEM (for Gasoline Model): HOW TO PROCEED WITH TROUBLESHOOTING; 2019 - 2022 MY Avalon [04/2018 - ]

HOW TO PROCEED WITH TROUBLESHOOTING

CAUTION / NOTICE / HINT

PRECAUTIONS WHEN TROUBLESHOOTING

NOTICE:

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.
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Before measuring the resistance of the CAN bus, turn the engine switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.
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(a) 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.

(b) The DLC3 inspection can only be used to detect malfunctions in the diagnosis bus (the bus which connects the DLC3 to the central gateway ECU (network gateway ECU)).

(c) 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 all the main bus lines are normal.)

(d) In the event of communication error history in the central bus, identify the ECUs or sensors which were not communicating by analyzing the combination of stored DTCs or by performing Communication Bus Check (Detail).

(e) 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.

HINT:

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

(f) 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.

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

PROCEDURE

1.	VEHICLE BROUGHT TO WORKSHOP

HINT:

If the engine switch can be turned to ON (the power source mode can be changed to on) 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 engine switch off until the inspection of the vehicle is finished, as some fail-safe functions are canceled when the engine switch is turned off.
If the engine switch cannot be turned to ON (the power source mode cannot be changed to on) when the vehicle is brought in, measure the voltage of the battery. If the voltage is below 11 V, recharge or replace the battery before performing troubleshooting.
If the engine switch cannot be turned to ON (the power source mode cannot be changed to on) even though the battery voltage is normal, repair this malfunction before performing troubleshooting.
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NEXT

2.	CUSTOMER PROBLEM ANALYSIS

HINT:

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 to the customer that the additional devices will be removed before performing troubleshooting as the malfunction cannot be checked properly.)
Examples of points to be confirmed are shown below.

(a) 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.

HINT:

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.)
Conditions when vehicle returned to normal (engine switch was turned off, etc.)

Points to be confirmed

Symptom

Air conditioning
- Whether the air conditioning system operated

- Whether the blower fan operated

- The air conditioning functions cannot be operated at all
Electric power steering
- Normal

- A little heavier than usual

- There was no assist
Drive monitor display
- Whether the update of multi-information display items stopped

- Whether the numeric part of the drivable distance was displayed

- Not displayed at all
Eco navigation (eco drive) display
- Whether the average fuel consumption graph is updated every minute

- Whether the updated section average fuel consumption graph is displayed

- Whether the distance-to-empty is displayed on the section average fuel consumption graph display

- Not displayed at all
Interior lights
- Whether the interior light illumination changes when the door is opened or closed

- Whether the interior lights turned off when the engine switch is turned on (IG)

- Not illuminated at all
Wireless door lock function and smart entry function
- Whether the lock/unlock function operated

- Whether the entry warning function operated

- Whether the illumination was turned on when the key was brought into a smart detection area
4WD/AWD operation
- Normal

- Slip detected when starting off
Memory call
- Normal

- Memory write error

- Memory read error

- Whether the auto return or auto away control is performed
Operation of other systems of concern

Meter warning lights

Illumination of warning lights and the order in which they illuminated
- Master

- Check engine (MIL)

- Brake

- ABS

- Slip

- EPS

- SRS

- Others
Meter display
- Speedometer

- Tachometer

- Engine coolant temperature gauge
Content displayed on the multi-information display
- Whether the odometer to TRIP meter has stopped

- Whether the value of the average fuel economy is displayed on the multi-information display

- Whether a warning message is displayed on the multi-information display

NEXT

3.

PRE-CHECK

(a) Measure the battery voltage with the engine switch off.

Standard Voltage:

11 to 14 V

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

HINT:

It can be determined if the battery is completely drained by operating the horn.
If the engine switch cannot be turned on (IG), measure the voltage of the battery. If it is below 11 V, perform inspection after replacing or recharging the battery.
If the engine switch cannot be turned on (IG) even though the battery voltage is normal, repair this malfunction before performing troubleshooting.
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NG

CHARGE OR REPLACE BATTERY

OK

4.	CHECK HARNESS AND CONNECTOR (BAT - GROUND)

(a) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
G45-16 (BAT) - Body ground	Always	11 to 14 V

*1

DLC3

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.	CHECK HARNESS AND CONNECTOR (CG - GROUND)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G45-4 (CG) - Body ground	Always	Below 1 Ω

*1

DLC3

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.	CHECK TECHSTREAM OPERATION

HINT:

Read the Techstream operator's manual before use.

Click here

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Check that the Techstream and ECUs can communicate with the engine switch on (IG).

HINT:

ECUs and sensors are not displayed on the "Communication Bus Check" screen when the Techstream cannot communicate with the vehicle.
If communication between the Techstream and ECUs is not possible, either the Techstream or vehicle has a malfunction.
If communication between the Techstream and ECUs is still not possible even when the Techstream is connected to another vehicle, the Techstream has a malfunction. Perform the self tests described in the Techstream operator's 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 not possible but communication is possible when connected to another vehicle.)	B
NG (Communication is not possible between the Techstream and the vehicle, nor between the Techstream and another vehicle.)	C

B

C

REFER TO TECHSTREAM OPERATOR'S MANUAL

A

7.	CHECK DTC (HEALTH CHECK)

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

NOTICE:

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 or sensor itself also cause these DTCs to be output.
If a CAN communication line connector is disconnected with the engine switch on (IG or ACC), the ECUs of the corresponding system and related systems store a DTC.

HINT:

If an open occurs in just one of the wires of a CAN branch line, 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.

(b) Read the freeze frame data using the Techstream and record it.

Result	Proceed to
OK (Only CAN communication DTCs are output.)	A
NG (DTCs other than CAN communication DTCs are also output.)	B

B

GO TO DIAGNOSTIC TROUBLE CODE CHART OF RELATED SYSTEM

A

8.	CHECK FOR DTCS (IDENTIFY ABNORMAL BUS)

(a) Proceed to the "Communication Malfunction Check" screen from the "Communication Bus Check" screen.

(b) Record all the DTCs stored for ECUs and sensors.

(c) Check if the stored DTCs are listed in the Diagnostic Trouble Code Chart of the CAN Communication System.

Click here

HINT:

For details on how to change to and from the "Communication Malfunction Check" screen, refer to Communication Bus Check (Communication Malfunction Check).
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For the definition of central bus, sub bus and local bus, refer to Definition of Terms.
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A sub bus monitoring ECU is a gateway function equipped ECU that monitors ECUs and sensors on its respective bus.
When the vehicle is equipped with a sub bus, refer to System Diagram to confirm the sub bus monitoring ECU.
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Sub bus monitoring ECUs monitor all ECUs and sensors connected to their respective sub bus and can accurately detect when an ECU or sensor stops communicating.
When CAN communication DTCs are stored but all ECUs and sensors connected to the CAN communication system are displayed as normal on the "Communication Bus Check" screen of the Techstream, a past malfunction is suspected.
When a sub bus monitoring ECU detects a communication error in the network, or that an ECU or sensor has stopped communicating, it stores a DTC.
When CAN communication DTCs are stored in an ECU connected to the central bus and in a sub bus monitoring ECU, inspect the corresponding sub bus and perform repairs if necessary before inspecting the central bus.
A malfunctioning local bus will not affect the central bus or sub buses.
When CAN communication DTCs are stored for a local bus, inspect related systems and perform repairs if necessary.

Result	Proceed to
The stored DTCs are not listed in the Diagnostic Trouble Code Chart for CAN Communication System.	A
The stored DTCs are listed in the Diagnostic Trouble Code Chart for CAN Communication System.	B

B

GO TO DIAGNOSTIC TROUBLE CODE CHART

A

9.	BUS INSPECTION (CHECK CONNECTED ECUS AND SENSORS USING TECHSTREAM)

(a) Based on the vehicle equipment and specifications, confirm the systems that use CAN communication.

Click here

(b) Select "CAN Bus Check" from the screen on the Techstream.

(c) Observe the screen for approximately 2 minutes to check the ECUs and sensors displayed on the screen.

(d) Check for ECUs or sensors with a background color that indicates that they are currently not communicating.

NOTICE:

A sub bus monitoring ECU outputs DTCs for its respective ECUs and sensors. Identify the malfunctioning ECU or sensor using the output DTCs.
ECUs or sensors that are not installed to the vehicle will not be displayed. Do not mistake these for ECUs or sensors that are not communicating.
When using the combo box, it may be possible to select a sub bus from the drop down list that does not have any connected ECUs or sensors. This is not a malfunction and occurs when there is no optional device connected to a sub bus which is monitored by a sub bus monitoring ECU (gateway function equipped ECU).

HINT:

For details on how to read the "Communication Bus Check" screen, refer to Description of "Communication Bus Check" screen.
Click here
If there is an ECU or sensor whose connection status changes intermittently while checking the "Communication Bus Check" screen, there may be an open circuit in one of the wires of a branch line of an ECU or sensor in the bus. If an open occurs in one of the wires of a CAN branch line, it may interfere with the communication of other ECUs or sensors resulting in an incorrect state being displayed.
The central gateway ECU (network gateway ECU) displays the connection status of ECUs and sensors connected to the central bus on the Techstream.
Sub bus monitoring ECUs display the connection status of ECUs and sensors connected to their respective sub bus on the Techstream.
If a CAN commutation DTC is output for an ECU connected to the sub bus, refer to the corresponding diagnostic procedure.
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Result

Proceed to

An ECU or sensor is not communicating

(An ECU or sensor has a red or red and yellow background)

A

All ECU and sensors are communicating

(All ECUs or sensors have a white or white and yellow background)

B

B

A

10.	CONFIRM PROBLEM SYMPTOMS (CHECK CONNECTED ECUS AND SENSORS USING TECHSTREAM)

(a) Confirm the suspected cause of the problem symptoms by referring to How to Use "Communication Bus Check" Screen in Inspection and using the result of Bus Inspection (Check Connected ECUs and Sensors Using Techstream).

HINT:

For details on how to inspect buses, refer to How to Use "Communication Bus Check" Screen in Inspection.
Click here
If there are multiple ECUs or sensors that are not communicating, check for blown fuses before proceeding with troubleshooting.
If there are multiple ECUs or sensors that are not communicating, after confirming that there are no power supply malfunctions, check for an open in CAN bus main lines, a short in CAN bus lines (CANH or CANL) or a short to ground or +B in CAN bus lines.
If there is an ECU or sensor that is not communicating, there may be an open circuit in one of the wires of its branch line. In this situation, the malfunctioning wire harness may affect noise immunity and interfere with the communication of other ECUs or sensors on the same bus. This may affect the validity of the displayed data.

Result	Proceed to
The problem symptom is found in the table for Problem Symptom Patterns other than Patterns A or B.	A
The problem symptom is not found in Problem Symptoms Table in How to Use "Communication Bus Check" Screen in Inspection. The problem symptom is found in the table for Problem Symptom Patterns A or B.	B

A

GO TO PROBLEM SYMPTOMS TABLE

B

11.	CAN BUS INSPECTION (DETERMINE CAUSE OF PROBLEM SYMPTOM)

(a) Disconnect the cable from the negative (-) battery terminal.

(b) Measure the resistance of any suspected buses that were specified by the result of Confirm Problem Symptoms (Check Connected ECUs and Sensors Using Techstream).

HINT:

For details on the terminal arrangement of the central gateway ECU (network gateway ECU), refer to Terminals of ECU.
Click here
If the CAN bus main line is normal and there is an ECU or sensor whose connection status changes intermittently while checking the "Communication Bus Check" screen, there may be an open circuit in one of the wires of a branch line of an ECU or sensor in the bus. If an open occurs in one of the wires of a CAN branch line, it may interfere with the communication of other ECUs or sensors resulting in an incorrect state being displayed.
Performing the bus inspection again may help in determining the suspected area.

Standard Resistance:

Tester Connection	Condition	Specified Condition	Result
CANH - CANL of a suspected bus	Cable disconnected from negative (-) battery terminal	54 to 69 Ω	Below 54 Ω: Short circuit between bus lines
CANH - CANL of a suspected bus	Cable disconnected from negative (-) battery terminal	54 to 69 Ω	70 Ω or higher: Open circuit in main bus lines
CANH - body ground of a suspected bus	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Below 200 Ω: CANH short to ground
CANL - body ground of a suspected bus	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Below 200 Ω: CANL short to ground
CANH - +B of a suspected bus	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short
CANL - +B of a suspected bus	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Below 6 kΩ: CANL +B short

Result	Proceed to
OK (CAN bus main lines are normal)	Go to Inspection for Open Circuit in a Branch Line
NG (There is an open or short in a CAN bus main line of a suspected bus)	Go to Respective Inspection

Go to Inspection for Open Circuit in a Branch Line

GO TO PROBLEM SYMPTOMS TABLE

Go to Respective Inspection

GO TO PROBLEM SYMPTOMS TABLE

12.	BUS INSPECTION (DETAIL) (CHECK CONNECTED ECUS AND SENSORS USING TECHSTREAM)

(a) Using the Techstream, display the "Communication Bus Check (Detail)" screen.

HINT:

For details on how to inspect buses using the "Communication Bus Check (Detail)" screen, refer to Description of "Communication Bus Check" Screen.

Click here

(b) Check the display for ECUs or sensors which have communication error history.

NOTICE:

ECUs or sensors that are not installed to the vehicle will not be displayed. Do not mistake these for ECUs or sensors that are not communicating.
When using the combo box, it may be possible to select a sub bus from the drop down list that does not have any connected ECUs or sensors. This is not a malfunction and occurs when there is no optional device connected to a sub bus which is monitored by a sub bus monitoring ECU (gateway function equipped ECU).

HINT:

The communication history of ECUs or sensors which have communication error history can be displayed on the "Communication Bus Check (Detail)" screen.
Lost Communication Time and Lost Communication Trip are only displayed for the central bus.
Lost Communication Time and Lost Communication Trip are not displayed for sub buses.

(c) Check for ECUs or sensors with a red background.

Result

Proceed to

An ECU or sensor has communication stop history.

(The background color of an ECU or sensor is red.)

A

No ECUs or sensors have communication stop history.

(The background color of an ECU or sensor is not red.)

B

B

A

13.	CONFIRM PROBLEM SYMPTOMS (CHECK CONNECTED ECUS AND SENSORS USING TECHSTREAM)

(a) Confirm the suspected cause of the problem symptoms by referring to How to Use "Communication Bus Check (Detail)" Screen in Inspection and using the result of Bus Inspection (Detail) (Check Connected ECUs and Sensors Using Techstream).

NOTICE:

ECUs or sensors that are not installed to the vehicle will not be displayed. Do not mistake these for ECUs or sensors that are not communicating.
When using the combo box, it may be possible to select a sub bus from the drop down list that does not have any connected ECUs or sensors. This is not a malfunction and occurs when there is no optional device connected to a sub bus which is monitored by a sub bus monitoring ECU (gateway function equipped ECU).

HINT:

For details on "Communication Bus Check (Detail)" screen, refer to How to Use "Communication Bus Check (Detail)" Screen in Inspection.
Click here
Lost Communication Time and Lost Communication Trip are only displayed for the central bus.
Lost Communication Time and Lost Communication Trip are not displayed for sub buses.
If an ECU or sensor has communication stop history, the background color of the ECU or sensor will be red.
If more than one ECU or sensor has a background color of red, check the values of Lost Communication Trip and Lost Communication Time. Communication error of an ECU or sensor with the value of Lost Communication Trip closest to the Current Trip and the largest value of Lost Communication Time is suspected.

Result	Proceed to
Suspected cause of problem symptom is found.	A
Suspected cause of problem symptom is not found.	B

A

GO TO PROBLEM SYMPTOMS TABLE

B

14.	CHECK DTC COMBINATION TABLE

(a) Determine the ECUs or sensors that were not communicating based on the combination of DTCs output from each ECU.

Click here

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

A

INSPECT FOR INTERMITTENT PROBLEMS

B

INSPECT PROBLEMS ACCORDING TO DTC COMBINATION TABLE

15.	CHECK HARNESS AND CONNECTOR (DLC3 - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

NOTICE:

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

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.

(a) Disconnect the cable from the negative (-) battery terminal.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G45-6 (CANH) - G45-14 (CANL)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω
G45-6 (CANH) - G45-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G45-14 (CANL) - G45-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G45-6 (CANH) - G45-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G45-14 (CANL) - G45-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

HINT:

If the resistance between CANH and CANL is not as specified, a connector may have been loose or disconnected during inspection. If a connector is loose or disconnected, connect it and perform the inspection again.

*1

DLC3

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (DLC3 - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

OK

16.	CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)

(a) Disconnect the G52 central gateway ECU (network gateway ECU) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G52-10 (GND) - Body ground	Cable disconnected from negative (-) battery terminal	Below 1 Ω

*a	Front view of wire harness connector (to Central Gateway ECU (Network Gateway ECU))

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND TERMINAL)

OK

17.	CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Reconnect the cable to the negative (-) battery terminal.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
G52-1 (BATT) - Body ground	Always	11 to 14 V
G52-2 (ACC) - Body ground	Engine switch on (ACC)	11 to 14 V
G52-11 (IG1) - Body ground	Engine switch on (IG)	11 to 14 V
G52-12 (IG2) - Body ground	Engine switch on (IG)	11 to 14 V

*a	Front view of wire harness connector (to Central Gateway ECU (Network Gateway ECU))

OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)