How To Proceed With Troubleshooting [11/2017 - 03/2019]: Procedure

VEHICLE BROUGHT TO WORKSHOP
HINT:
- If the engine 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 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 on (IG) (the power source mode cannot be changed to on (IG)) 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 on (IG) even though the battery voltage is normal, repair this malfunction before performing troubleshooting.
  Refer to PROBLEM SYMPTOMS TABLE [09/2014 - ]
Result

Result

NEXT

Result:

NEXT

See step 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.

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.)
Return conditions (what made the vehicle return to normal, for example, the engine 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 air conditioning function can be operated by the LEXUS display audio controller or Remote Touch

- Whether the blower fan operated
Drive monitor display
- Whether the update of multi-information display items stopped

- Whether the numeric part of the drivable distance was displayed
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
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 entry warning function operated

- Whether the illumination was turned on when the key was brought into a smart detection area
Power tilt and telescopic system
- Whether the driving position memory/restoring, auto away/return functions operated
Seat
- Whether the driving position memory call, auto away/return functions operated
Operation of other systems of concern

Meter warning lights

Illumination of warning lights and the order in which they illuminated
- Check engine (MIL)

- ABS

- SRS

- EPS

- Slip

- Master

- Brake

- Auto leveling

- PCS

- Cruise

- Others
Meter display
- Speedometer

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

Result

Proceed to
NEXT

Result:

See step 3

CHECK TECHSTREAM

HINT:

Read the Techstream operator's manual before use.

Refer to GENERAL INFORMATION [09/2014 - ]

Connect the Techstream to the DLC3.
Turn the engine switch on (IG).
Turn the Techstream on.

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

HINT:

If communication is not possible, the Techstream screen will indicate an error.
If communication between the Techstream and ECUs is not possible, either the Techstream or vehicle has a malfunction.
When communication between the Techstream and the vehicle is not possible, 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 25 to 26 first). In addition, check that the BAT terminal of the DLC3 receives battery voltage (11 V or more).
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

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

Result:

See step 25

Result:

REFER TO TECHSTREAM OPERATOR'S MANUAL

Result:

See step 4

CHECK DTC (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

Connect the Techstream to the DLC3.
Turn the engine switch on (IG).
Turn the Techstream on.

Enter the following menus: Body Electrical / Central Gateway / Trouble Codes.

DTC B1003 is not output.

Body Electrical > Central Gateway > Trouble Codes

Result

Result
OK
NG

Result:

See step 6

Result:

See step 5

CHECK DTC

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 or sensor itself also cause these DTCs to be output.
- If a CAN communication line connector is disconnected with the engine switch on (IG), the ECUs of the corresponding system and related systems store a DTC.
HINT:
- If an open in a CAN main bus line, a short between the CAN bus lines (CANH and CANL) or a short to ground or +B 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 10 to 18) first.
- 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.

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

Result

Proceed to
NEXT

Result:

See step 8

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

Replace the central gateway ECU (network gateway ECU).

Refer to REMOVAL [11/2017 - ]

HINT:

DTC B1003 is stored when a malfunction is detected in the non-volatile storage of the central gateway ECU (network gateway ECU). As DTC B1003 is not related to a communication malfunction, continue with troubleshooting to find the cause of the communication malfunction after replacing the central gateway ECU (network gateway ECU).

Result

Proceed to
NEXT

Result:

See step 7

CHECK DTC

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 or sensor itself also cause these DTCs to be output.
- If a CAN communication line connector is disconnected with the engine switch on (IG), the ECUs of the corresponding system and related systems store a DTC.
HINT:
- If an open in a CAN main bus line, a short between the CAN bus lines (CANH and CANL) or a short to ground or +B 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 10 to 18) first.
- 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.

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

Result

Proceed to
NEXT

Result:

See step 8

PERFORM COMMUNICATION MALFUNCTION CHECK (CONNECTION STATUS CHECK USING TECHSTREAM)

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

Record all the DTCs stored for ECUs and sensors.

Result

Proceed to
NEXT

Result:

See step 9

PERFORM CAN BUS CHECK (CONNECTION STATUS CHECK USING TECHSTREAM)

Based on the vehicle equipment and specifications, confirm the systems that use CAN communication.
Refer to DIAGNOSIS SYSTEM [11/2017 - 03/2019]
Select "CAN Bus Check" from the screen on the Techstream.
CAN Bus Check

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

Result

Proceed to
NEXT

Result:

See step 10

CHECK BUS 2 MAIN LINE (CANH - CANL)

NOTE:

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.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-18 (CA4H) - O145-17 (CA4L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))

Result

Result	Proceed to
OK	A
NG (70 Ω or higher)	B
NG (Below 54 Ω)	C

Result:

GO TO OPEN IN BUS 2 MAIN BUS LINE. Refer to Open in Bus 2 Main Bus Line [11/2017 - ]

Result:

GO TO SHORT IN BUS 2 LINES. Refer to Check Bus 2 Lines for Short Circuit [11/2017 - 03/2019]

Result:

See step 11

CHECK FOR SHORT TO GND IN BUS 2 (CANH, CANL - CG)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	DLC3	-	-
*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-18 (CA4H) - O8-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
O145-17 (CA4L) - O8-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

Result

Result
OK
NG

Result:

GO TO SHORT TO GND IN BUS 2 LINE. Refer to Check Bus 2 Line for Short to GND [11/2017 - 03/2019]

Result:

See step 12

CHECK FOR SHORT TO +B IN BUS 2 (CANH, CANL - BAT)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	DLC3	-	-
*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-18 (CA4H) - O8-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
O145-17 (CA4L) - O8-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

Result

Result
OK
NG

Result:

GO TO SHORT TO +B IN BUS 2 LINE. Refer to Check Bus 2 Line for Short to +B [11/2017 - 03/2019]

Result:

See step 13

CHECK BUS 3 MAIN LINE (CANH - CANL)

NOTE:

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.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-6 (CA3H) - O145-21 (CA3L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))

Result

Result	Proceed to
OK	A
NG (70 Ω or higher)	B
NG (Below 54 Ω)	C

Result:

GO TO OPEN IN BUS 3 MAIN BUS LINE. Refer to Open in Bus 3 Main Bus Line [11/2017 - 03/2019]

Result:

GO TO SHORT IN BUS 3 LINES. Refer to Check Bus 3 Lines for Short Circuit [11/2017 - 03/2019]

Result:

See step 14

CHECK FOR SHORT TO GND IN BUS 3 (CANH, CANL - CG)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	DLC3	-	-
*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-6 (CA3H) - O8-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
O145-21 (CA3L) - O8-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

Result

Result
OK
NG

Result:

GO TO SHORT TO GND IN BUS 3 LINE. Refer to Check Bus 3 Line for Short to GND [11/2017 - 03/2019]

Result:

See step 15

CHECK FOR SHORT TO +B IN BUS 3 (CANH, CANL - BAT)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	DLC3	-	-
*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-6 (CA3H) - O8-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
O145-21 (CA3L) - O8-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

Result

Result
OK
NG

Result:

GO TO SHORT TO +B IN BUS 3 LINE. Refer to Check Bus 3 Line for Short to +B [11/2017 - 03/2019]

Result:

See step 16

CHECK BUS 5 MAIN LINE (CANH - CANL)

NOTE:

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.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-15 (CA5H) - O145-16 (CA5L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))

Result

Result	Proceed to
OK	A
NG (70 Ω or higher)	B
NG (Below 54 Ω)	C

Result:

GO TO OPEN IN BUS 5 MAIN BUS LINE. Refer to Open in Bus 5 Main Bus Line [11/2017 - 09/2020]

Result:

GO TO SHORT IN BUS 5 LINES. Refer to Check Bus 5 Lines for Short Circuit [11/2017 - 09/2020]

Result:

See step 17

CHECK FOR SHORT TO GND IN BUS 5 (CANH, CANL - CG)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	DLC3	-	-
*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-15 (CA5H) - O8-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
O145-16 (CA5L) - O8-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

Result

Result
OK
NG

Result:

GO TO SHORT TO GND IN BUS 5 LINE. Refer to Check Bus 5 Line for Short to GND [11/2017 - 03/2019]

Result:

See step 18

CHECK FOR SHORT TO +B IN BUS 5 (CANH, CANL - BAT)

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*1	DLC3	-	-
*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-15 (CA5H) - O8-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
O145-16 (CA5L) - O8-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

Result

Result
OK
NG

Result:

GO TO SHORT TO +B IN BUS 5 LINE. Refer to Check Bus 5 Line for Short to +B [11/2017 - 03/2019]

Result:

See step 19

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

Inspect or repair the probable malfunctioning part based on the check result of step 9 (the step in which CAN bus check was performed).

CAN Bus Check

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 as normal on the screen. (CAN bus circuit is currently normal.)	A
All ECUs except the main body ECU (multiplex network body ECU) connected to sub bus 1 are displayed as communication stop on the screen. The main body ECU (multiplex network body ECU) (Main Body) outputs DTC U1002. (Open or short in sub bus 1 main lines.)	B
The main body ECU (multiplex network body ECU) is displayed as communication stop on the screen, and all ECUs except the main body ECU (multiplex network body ECU) connected to sub bus 1 are not displayed on the screen. (Open in main body ECU (multiplex network body ECU) branch lines or main body ECU (multiplex network body ECU) malfunction.)	C
When the bus 2 is selected using the pull down menu, all the ECUs and sensors connected to the bus 2 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.)	D
The bus 2 main line is normal. All ECUs or sensors except central gateway ECU (network gateway ECU) connected to bus 2 are displayed as communication stop on the screen. (Open in central gateway ECU branch lines or central gateway ECU (network gateway ECU) malfunction.)	E
One of the ECUs or sensors connected to the bus 2, bus 3 or bus 5 is displayed as communication stop on the screen. (Open in ECU or sensor branch lines, or communication is interrupted.)	F
One of the ECUs or sensors connected to sub bus 1 is displayed as communication stop 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 bus 2 but are displayed as communication stop 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
In addition to ECUs and sensors which are connected to the bus 3 but are displayed as communication stop 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.)	I
In addition to ECUs and sensors which are connected to the bus 5 but are displayed as communication stop 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.)	J

NOTE:

*: In this case, as the main body ECU (multiplex network body ECU) (Main Body) 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.)

HINT:

Regarding CAN Bus Check, refer to How to Interpret CAN Bus Check Screen.
Refer to DIAGNOSIS SYSTEM [11/2017 - 03/2019]
If the detection status of any ECU 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 1, the main body ECU (multiplex network body ECU) displays communicating ECUs on the Techstream. If the communication between the main body ECU (multiplex network body ECU) and an ECU stops for 10 seconds or more, the ECU will no longer be displayed on the Techstream.
Regarding the communication stop mode for ECUs connected to sub bus 1, refer to the inspection procedure for the DTCs that indicate a communication stop.

Result:

GO TO U1002 (Main Body). Refer to DTC U1002: Lost Communication with Gateway Module (Main Body ECU) [11/2017 - 03/2019]

Result:

GO TO MAIN BODY ECU COMMUNICATION STOP MODE. Refer to Main Body ECU Communication Stop Mode [11/2017 - ]

Result:

GO TO SFI SYSTEM. Refer to DTC U0101: Lost Communication with TCM [09/2014 - ]

Result:

GO TO CENTRAL GATEWAY ECU COMMUNICATION STOP MODE. Refer to Central Gateway ECU Communication Stop Mode [11/2017 - ]

Result:

GO TO COMMUNICATION STOP MODE TABLE. Refer to PROBLEM SYMPTOMS TABLE [11/2017 - 03/2019]

Result:

GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to DIAGNOSTIC TROUBLE CODE CHART [11/2017 - 03/2019]

Result:

GO TO OPEN IN ONE SIDE OF BUS 2 BRANCH LINE. Refer to Open in One Side of Bus 2 Branch Line [11/2017 - 03/2019]

Result:

GO TO OPEN IN ONE SIDE OF BUS 3 BRANCH LINE. Refer to Open in One Side of Bus 3 Branch Line [11/2017 - ]

Result:

GO TO OPEN IN ONE SIDE OF BUS 5 BRANCH LINE. Refer to Open in One Side of Bus 5 Branch Line [11/2017 - 01/2023]

Result:

See step 20

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

Inspect or repair the probable malfunctioning part based on the check result of step 8 (the step in which checking for communication malfunction DTCs was performed).

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 bus 2, bus 3 or bus 5 have stored communication DTCs. (A malfunction occurred in the bus 2, bus 3 or bus 5.)	A
The main body ECU (multiplex network body ECU) (Main Body) outputs DTC U1002. (A malfunction occurred in sub bus 1.)	B
One or more communication error DTCs for an ECU or sensor connected to Sub Bus 1 are output, but DTC U1002 is not output by the main body ECU (multiplex network body ECU) (Main Body). (A malfunction occurred in an ECU branch line connected to sub bus 1.)	C
The torque vectoring differential ECU assembly (TVD) outputs only DTC U1172. The skid control ECU (brake actuator assembly) (ABS/VSC/TRAC) outputs only DTC U110F. (A malfunction occurred in V3 bus.)	D
The ECM (Engine) outputs only DTC U0101. The TCM (ECT) outputs only DTC U0100. (A malfunction occurred in sub bus 15.)	E

HINT:

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).
Refer to DIAGNOSIS SYSTEM [11/2017 - 03/2019]
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.
Refer to DIAGNOSIS SYSTEM [11/2017 - 03/2019]
If communication DTCs are stored, and all ECUs and sensors connected to the CAN communication system are displayed on the CAN Bus Check screen of the Techstream, a past malfunction that is currently not occurring is suspected.
When a CAN branch of the bus 2, bus 3 or bus 5 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 1 is malfunctioning, the main body ECU (multiplex network body ECU) detects a communication stop for connected ECUs and a network communication error, and stores DTCs.
On the Techstream, the Main Body item displays the DTCs for ECUs connected to sub bus 1.
When both the sub bus monitor ECU and the ECUs connected to the bus 2, bus 3 or bus 5 store communication DTCs, check and repair the corresponding sub bus first.

Result:

GO TO U1002 (Main Body). Refer to DTC U1002: Lost Communication with Gateway Module (Main Body ECU) [11/2017 - 03/2019]

Result:

GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to DIAGNOSTIC TROUBLE CODE CHART [11/2017 - 03/2019]

Result:

GO TO U110F. Refer to DTC U110F: Lost Communication With Roll Rate Sensor/Vertical Acceleration Sensor Module; DTC U1172: Lost Communication with Vehicle Dynamics Control Module (ch2) [11/2017 - 03/2019]

Result:

GO TO SFI SYSTEM. Refer to DTC U0101: Lost Communication with TCM [09/2014 - ]

Result:

See step 21

DTC COMBINATION TABLE

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

Refer to DTC COMBINATION TABLE [11/2017 - 03/2019]

Result

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

HINT:

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 the CAN Bus Check screen of the Techstream.

Result:

GO TO COMMUNICATION STOP MODE TABLE. Refer to PROBLEM SYMPTOMS TABLE [11/2017 - 03/2019]

Result:

See step 22

IDENTIFICATION OF PROBLEM (PAST MALFUNCTION IN MAIN BUS OF BUS 2, BUS 3 OR BUS 5)

Connect the cable to the negative (-) battery terminal.
Clear the DTCs using the Techstream.
Perform the tests in Symptom Simulation to check the wire harnesses and connectors including those for main bus lines.
Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2017 - 03/2019]

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

HINT:

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

Result

Proceed to
NEXT

Result:

See step 23

REPAIR OR REPLACEMENT
Result

Proceed to

NEXT

Result:

NEXT

See step 24
CONFIRMATION TEST
Result

Proceed to

NEXT

Result:

NEXT

END

CHECK V BUS BRANCH LINE (DLC3 - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

NOTE:

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.

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

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

Standard Resistance

Tester Connection	Condition	Specified Condition
O8-6 (CANH) - O8-14 (CANL)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω
O8-6 (CANH) - O8-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
O8-14 (CANL) - O8-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
O8-6 (CANH) - O8-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
O8-14 (CANL) - O8-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

DLC3

Result

Result
OK
NG

Result:

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) - DLC3)

Result:

See step 26

CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

Disconnect the O145 central gateway ECU (network gateway ECU) connector.

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

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

Standard Resistance

Tester Connection	Condition	Specified Condition
O145-10 (GND) - Body ground	Cable disconnected from negative (-) battery terminal	Below 1 Ω

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

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

Standard Voltage

Tester Connection	Condition	Specified Condition
O145-1 (BATT) - Body ground	Always	11 to 14 V
O145-2 (ACC) - Body ground	Engine switch on (ACC)	11 to 14 V
O145-11 (IG1) - Body ground	Engine switch on (IG)	11 to 14 V
O145-12 (IG2) - Body ground	Engine switch on (IG)	11 to 14 V

Result

Result
OK
NG

Result:

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU). Refer to REMOVAL [11/2017 - ]

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)