Part 1

NETWORKING: CAN COMMUNICATION SYSTEM: DIAGNOSIS SYSTEM

1. ECUS OR SENSORS WHICH COMMUNICATE THROUGH CAN COMMUNICATION SYSTEM

(a) V Bus

(1) ECM

(2) Brake booster with master cylinder assembly (Skid control ECU)

(3) Main body ECU (Multiplex network body ECU)

(4) Yaw rate sensor

(5) Power steering ECU assembly

(6) Smart key ECU assembly (Certification ECU)

(7) Airbag ECU assembly

(8) Spiral cable with sensor sub-assembly (Steering angle sensor)

(9) Power management control ECU

(10) Transmission control ECU assembly

(11) Meter circuit plate

(12) Navigation computer sub-assembly*1

(13) Radio and display receiver assembly*2

(b) Sub bus 11

(1) Power management control ECU

(2) Driving support ECU assembly*3

(3) Seat belt control ECU*4

(4) Parking assist ECU*5

(c) Sub bus 12

(1) Power management control ECU

(2) ECM

(3) Brake booster with master cylinder assembly (Skid control ECU)

(4) Air conditioning amplifier assembly

HINT
*1: for Navigation receiver type

*2: for Radio and display type

*3: w/ Dynamic radar cruise control system

*4: w/ Pre-collision system

*5: w/ Advanced parking guidance system

2. CHECK FOR INSTALLED SYSTEMS (ECUS AND SENSORS) THAT ADOPT CAN COMMUNICATION

(a) 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.

HINT
The names of ECUs and sensors shown on the Techstream display may differ from those shown in the DTC Table by ECU section that follows.

3. CAN BUS CHECK

HINT
The ECUs and sensors that are properly connected to the CAN communication system can be displayed using the Techstream.

(a) Using the Techstream, select "CAN Bus Check" from "System Select".

NOTICE:
* It may be possible to select buses that do not have ECUs or sensors from the bus selection pull-down menu. 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.)
* In the bus selection pull down menu, all buses applicable to the model are displayed (e.g. LIN communication buses are also displayed). Therefore, refer to the wiring diagrams to check the names of sub buses for CAN communication System Diagram.

HINT
Different connection statuses are indicated by the background color of ECUs and sensors that are displayed.

Explanation of CAN Bus Check (Communication Bus Check) screen

HINT
* Gateway function equipped ECUs relay signals between the ECUs connected to the different buses.
* *1: ECUs that are present in the vehicle but are not displayed on the CAN Bus Check.
* *2: Gateway function equipped ECU that does not memorize the sub bus ECUs that are connected to it.
* *3: Gateway function equipped ECU that memorizes the sub bus ECUs that are connected to it.
* If none of the connected ECUs are displayed, or there is no response from the vehicle to the Techstream, check the DLC3 branch and the V bus main bus lines for a malfunction.

(b) Observe the connection response screen for approximately 2 minutes to check for a change in connection status of the connected ECUs and sensors.

HINT
* If an open occurs in one of the lines of a CAN branch (except DLC3), output from the other branch line (the line that is not open) will be unstable and it may interfere the response (display) of other ECUs and sensors.
* If the connection status changes during the inspection, repair the open in the branch line of the ECU or sensor that does not respond (is not detected) and then perform the CAN bus check again.

4. HOW TO INTERPRET CAN BUS CHECK (COMMUNICATION BUS CHECK) SCREEN

(a) When a communication stop is currently occurring, the probable malfunctioning part can be determined from the CAN bus check and by using the following methods.

NOTICE:
The following CAN bus wiring diagram is provided only as an example. This wiring diagram is different from the actual wiring diagram for this vehicle.

HINT
* When a communication stop is currently occurring, it is easier to determine the probable malfunctioning part from the CAN bus check rather than from communication DTCs.
* Wait for approximately 2 minutes after turning the power switch on (IG) (or simulate the driving conditions that enable the malfunction to be reproduced) and select the CAN bus check. Then observe the communication status of each ECU on the screen.

(b) If a communication error of only 1 ECU or sensor is indicated on the CAN Bus Check screen, a communication stop of the ECU or sensor is suspected.

Example: Open in both CAN branch lines of ECU B on the V bus

Text in Illustration

HINT
When there are communication stops, ECUs are present in the vehicle even though they are not displayed on the CAN Bus Check screen.

(c) If communication errors for multiple ECUs or sensors are indicated on the CAN Bus Check screen, then a communication stop of the ECU or sensor that shows a more serious communication stop (an ECU or a sensor which is not displayed) is suspected.

Example: Open in a CAN branch line for ECU D on the V bus

Text in Illustration

Explanation of CAN Bus Check (Communication Bus Check) screen

Text in Illustration

HINT
* In the CAN bus check, it is possible to confirm the communication status of ECUs connected to the V bus after connecting the Techstream to the DLC3. As for sub buses, it is possible to confirm which sub bus connected ECUs can communicate with a gateway function equipped ECU on the V bus.
* If a gateway function equipped ECU has a communication error, ECUs connected to the gateway function equipped ECU are also affected, and communication stops will be indicated.
* The CAN Bus Check screen in the illustration shows that ECU C has a gateway function and a communication stop in ECU C is suspected.

(e) If the CAN Bus Check screen indicates a communication stop only in the sub bus, a communication stop in the sub bus is suspected.

Example: Open in both CAN branch lines of ECU G on the sub bus

Text in Illustration

HINT
* A communication error in a sub bus does not affect the V bus or other buses.
* When a gateway function equipped ECU has memorized the ECUs that are connected to the sub bus, if any of the ECUs connected to the gateway function equipped ECU has a communication error, the background color changes to yellow or red. (The displayed name will not disappear.)

(f) If both of the V bus main bus lines are open, ECUs or sensors that are located farther away from the DLC3 than the open part will be displayed as a communication stop on the CAN Bus Check screen.

(In this case, ECU A and B are not displayed or their background color changes to red.)

Text in Illustration

HINT
If a communication error occurs in an ECU, it is not displayed on the CAN Bus Check screen even though the ECU is present.

(g) If both of the sub bus main bus lines are open, ECUs that are located farther away from the gateway function equipped ECU than the open part will be displayed as a communication stop on the CAN Bus Check screen.

(In this case, ECU I and J are not displayed or their background color changes to red.)

Text in Illustration

(h) When any of the following malfunctions occur, CAN communication cannot be established and almost all ECUs and sensors on the bus show a communication error on the CAN Bus Check screen.

Text in Illustration

Details of Malfunction

HINT
* When a malfunction occurs on the V bus, almost all ECUs and sensors on the V bus and sub bus indicate a communication error (almost all ECUs are not displayed). As communication with the gateway function equipped ECU that is connected to the V bus stops, communication from the ECUs connected to the sub bus that is monitored by the gateway function equipped ECU also stops (these ECUs are not displayed).
* When a malfunction occurs in a sub bus, almost all ECUs connected to the sub bus indicate a communication error.
* A communication error in a sub bus does not affect the V bus or other buses.
* The malfunctioning part can be determined by checking for a short circuit between CAN bus lines or between a CAN bus line and ground or +B short using an electrical tester.

5. HOW TO INTERPRET COMMUNICATION DTCS (DTCS THAT START WITH U)

(a) If a CAN communication error cannot be reproduced, determine the suspected malfunctioning part using the DTCs stored in ECUs that are connected to the CAN buses by following the procedure below.

HINT
Communication DTCs (DTCs that start with U) indicate a communication error between the ECU that stores the DTC and the ECU that is indicated by the DTC.

(1) If multiple ECUs store a communication DTC for a particular ECU, a communication stop of the ECU is suspected.

Text in Illustration

NOTICE:
* This DTC table is from another model, and is only used here to show an example of DTCs that are output when there is an open in a CAN branch line for the main body ECU. This table does not show DTCs applicable to this vehicle.
* Even though a DTC title may indicate a communication error with a specific ECU, the ECU name used in the DTC name on the Techstream may differ depending on the ECU that stores the DTC. (Regarding output DTCs, refer to step 6 and the DTC chart for each ECU.)

HINT
As multiple ECUs indicate a communication stop with the main body ECU, the possibility of a communication stop of the main body ECU is high.

(2) If almost all of the communication DTCs of an ECU are stored, a communication stop of the ECU is suspected.

Text in Illustration

NOTICE:
This DTC table is from another model, and is only used here to show an example of DTCs that are output when there is an open in a CAN branch line for the main body ECU. This table does not show DTCs applicable to this vehicle.

HINT
If almost all of the DTCs of the main body ECU are stored, the possibility of a communication stop of the main body ECU is high.

(3) When a CAN communication error occurs, many DTCs are output. DTCs other than communication error DTCs (such as DTCs that start with C or B) and communication DTCs for the ABS system are important DTCs, however it may be easier to determine the malfunctioning part by examining the overall situation without considering these DTCs.

(b) To help determine the part of the sub bus that has a communication error, prioritize the communication stop DTCs stored in the gateway function equipped ECU.

Text in Illustration

NOTICE:
This DTC table is from another model, and is only used here to show the ECUs connected to both a V bus and a sub bus. It shows DTCs output when there is an open in the main bus lines for the ECM on the sub bus. This table does not show DTCs applicable to this vehicle.

HINT
* As gateway function equipped ECUs (sub bus monitor ECU) monitor signals from all ECUs that are connected to sub buses, gateway function equipped ECUs can detect ECUs with a communication stop more accurately.
* When there is a communication stop for the gateway function equipped ECU (gateway), communication with ECUs connected to other buses such as the V bus stops. Therefore, communication DTCs for ECUs connected to other buses are also stored.

(c) When any of the following malfunctions occurs, many DTCs are likely to be output from many ECUs. Because of this, it may be difficult to determine the probable malfunctioning part.

* Short between CAN lines (CANH and CANL)

* Short between a CAN line (CANH or CANL) and ground

* Short between a CAN line (CANH or CANL) and +B

* Open in a CAN branch line (CANH or CANL) of an ECU or sensor

* Open in a CAN main bus line (CANH or CANL) between 2 ECUs that have a terminating resistor

6. DTC TABLE BY ECU

HINT
* In the CAN communication system, the CAN communication DTCs of each ECU can be displayed using the Techstream.
* If CAN communication system DTCs are output, trouble cannot be determined only by the DTCs. Perform troubleshooting according to How to Proceed with Troubleshooting How to Proceed With Troubleshooting.
* If system function temporarily returns to normal, DTCs may not be output again even though the following DTC check procedures are used.

(a) Power Management Control ECU / Techstream Display "Hybrid Control"

Power Management Control ECU / Techstream Display "Hybrid Control"

HINT
* This ECU uses the CAN communication system for DTC communication.
* The power management control ECU stores DTCs for the dynamic radar cruise control system.
* *1: This DTC is not for a malfunction of CAN communication but for an error for one-to-one serial communication Hybrid Control System.
* *2: This DTC is not for a malfunction of CAN communication but for an error for one-to-one serial communication Hybrid Battery System.
* *3: Dynamic radar cruise control system DTC.
* *4: Even though a communication error is indicated on the Techstream, the power management control ECU stores this DTC when it detects an internal malfunction in the air conditioning amplifier assembly.

(b) Power Management Control ECU / Techstream Display "Power Source Control"

Power Management Control ECU / Techstream Display "Power Source Control"

HINT
* This ECU uses the CAN communication system for DTC communication.
* The HV CPU and power management CPU are built into the power management control ECU.
* *1: If U0293 is output alone, CAN communication is normal.

(c) Power Management Control ECU / Techstream Display "Cruise Control"

Power Management Control ECU / Techstream Display "Cruise Control"

HINT
* This ECU uses the CAN communication system for DTC communication.
* The power management control ECU stores DTCs for the cruise control system.
* *1: Cruise control system DTC.

(d) Power Management Control ECU / Techstream Display "PM1 Gateway"

Power Management Control ECU / Techstream Display "PM1 Gateway"

HINT
* This ECU uses the CAN communication system for DTC communication.
* "PM1 Gateway" output DTC is communication error in the Sub bus 11.

(e) Power Management Control ECU / Techstream Display "PM2 Gateway"

Power Management Control ECU / Techstream Display "PM2 Gateway"

HINT
* This ECU uses the CAN communication system for DTC communication.
* "PM2 Gateway" output DTC is communication error in the Sub bus 12.

(f) ECM / Techstream Display "Engine"

ECM / Techstream Display "Engine"

HINT
This ECU uses the CAN communication system for DTC communication.

(g) Transmission Control ECU Assembly / Techstream Display "Transmission Control"

Transmission Control ECU Assembly / Techstream Display "Transmission Control"

HINT
This ECU uses the CAN communication system for DTC communication.

(h) Power Steering ECU / Techstream Display "EMPS"

Power Steering ECU / Techstream Display "EMPS"

HINT
This ECU uses the CAN communication system for DTC communication.

(i) Brake booster with master cylinder (Skid control ECU) / Techstream Display "ABS/VSC/TRAC"

Brake booster with master cylinder (Skid control ECU) / Techstream Display "ABS/VSC/TRAC"

HINT
This ECU uses the CAN communication system for DTC communication.

(j) Steering Angle Sensor / Techstream Display "Steering Angle Sensor"

HINT
The steering angle sensor is connected to the CAN communication system, but CAN communication DTCs are not output.

(k) Yaw Rate Sensor / Techstream Display "Yaw Rate / Deceleration Sensor"

HINT
The yaw rate sensor is connected to the CAN communication system, but CAN communication DTCs are not output.

(l) Center Airbag Sensor Assembly / Techstream Display "SRS Airbag"

HINT
The center airbag sensor assembly is connected to the CAN communication system, but CAN communication DTCs are not output.

(m) Main Body ECU (Multiplex network body ECU) / Techstream Display "Main Body"

Main Body ECU (Multiplex network body ECU) / Techstream Display "Main Body"

HINT
This ECU uses the CAN communication system for DTC communication.

(n) Smart key ECU assembly (Certification ECU) / Techstream Display "Smart Key"

Smart key ECU assembly (Certification ECU) / Techstream Display "Smart Key"

HINT
This ECU uses the CAN communication system for DTC communication.

(o) Air Conditioning Amplifier Assembly / Techstream Display "Air Conditioner"

Air Conditioning Amplifier Assembly / Techstream Display "Air Conditioner"

HINT
This ECU uses the CAN communication system for DTC communication.

(p) Meter Circuit Plate / Techstream Display "Combination Meter"

Meter Circuit Plate / Techstream Display "Combination Meter"

HINT
This ECU uses the CAN communication system for DTC communication.

(q) Navigation Computer Sub-Assembly / Techstream Display "Navigation System"

Navigation Computer Sub-Assembly / Techstream Display "Navigation System"

HINT
This ECU uses the CAN communication system for DTC communication.

(r) Radio and Display Receiver Assembly / Techstream Display "Navigation System"

Radio and Display Receiver Assembly / Techstream Display "Navigation System"

HINT
This ECU uses the CAN communication system for DTC communication.

(s) Seat Belt Control ECU / Techstream Display "Pre-Collision"

Seat Belt Control ECU / Techstream Display "Pre-Collision"

HINT
This ECU uses the CAN communication system for DTC communication.

(t) Driving Support ECU Assembly / Techstream Display "Pre-Collision2"

Driving Support ECU Assembly / Techstream Display "Pre-Collision2"

HINT
* DTC communication uses the CAN communication system.
* *1: If U0235 is output alone, CAN communication is normal. Refer to Pre-Collision System Pre-Collision System.
* *2: If U1104 is output alone, CAN communication is normal. Refer to Pre-Collision System Pre-Collision System.

(u) Driving Support ECU Assembly / Techstream Display "Radar Cruise"

Driving Support ECU Assembly / Techstream Display "Radar Cruise"

HINT
* This ECU uses the CAN communication system for DTC communication.
* *1: If U0235 is output alone, CAN communication is normal. Refer to Dynamic Radar Cruise Control System Dynamic Radar Cruise Control System.
* *2: If U1104 is output alone, CAN communication is normal. Refer to Dynamic Radar Cruise Control System Dynamic Radar Cruise Control System.

(v) Parking Assist ECU / Techstream Display "Advanced Parking Guidance System"

Parking Assist ECU / Techstream Display "Advanced Parking Guidance System"

HINT
* This ECU uses the CAN communication system for DTC communication.
* *4: If U1000 is output alone, CAN communication is normal. Refer to Advanced Parking Guidance System U1000.

7. DTC COMBINATION TABLE (OPEN IN CAN BRANCH OF V BUS, PAST COMMUNICATION ERROR)

(a) Regarding the past communication error of ECUs and sensors connected to the V bus (in this case, normal was displayed when performing the CAN bus check, but communication DTCs are output), the probable CAN branch that had a malfunction can be determined based on the following DTC combination table.

HINT
* Based on the table below and DTCs output from ECUs connected via CAN communication, the probable part for which communication stop occurred can be determined.
* Regarding an open in a CAN branch and a communication stop that is currently occurring, the malfunctioning part can be confirmed easily by performing the CAN bus check using the Techstream because the ECU or sensor connected to the CAN branch does not respond (the ECU or sensor name will not be displayed on the screen).
* 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 the CAN bus occurs, DTCs of almost all ECUs (or 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.

HINT
* o: Set
* X: Not set or may be set according to the malfunctioning part when one line of a CAN branch is open.
* -: DTC is not output.
* *1: DTC is not output during communication error, but will be output as a history DTC (past DTC) when communication returns to normal.
* *2: DTC U0123, U0124, U0126 and U0293 are not stored when DTC U0073 has already been stored.