Lexus ES: Bus Buffer ECU Communication Stop Mode

Lexus ES (XZ10) Service Manual / Power Source & Network / Networking / Can Communication System (for Gasoline Model) / Bus Buffer ECU Communication Stop Mode

DESCRIPTION

Detection Item	Symptom	Trouble Area
Bus Buffer ECU Communication Stop Mode	Any of the following conditions are met: Communication stop for "Accessory Gateway" is indicated on the "Communication Bus Check" screen of the Techstream. Click here Communication stop history for "Accessory Gateway" is indicated on the "Communication Bus Check (Detail)" screen of the Techstream. (The Lost Communication Time value for "Accessory Gateway" is 6 or more.) Click here Communication system DTCs (DTCs that start with U) that correspond to "Bus Buffer ECU Communication Stop Mode" in "DTC Combination Table" are output. Click here	Option connector (bus buffer ECU) branch line or connector CAN compatible optional device Power source circuit of option connector (bus buffer ECU) Option connector (bus buffer ECU) ground circuit

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

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.
Click here
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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After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.
DTC check procedure: Turn the engine switch on (IG) and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 5 minutes or more.
After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.
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HINT:

Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.
When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE

1.	CHECK OPTIONS

(a) Check whether dealer installed options that support CAN communication are installed.

Result	Proceed to
Installed	A
Not installed	B

GO TO STEP 4

2.	CHECK FOR OPEN IN CAN BUS LINES (OPTION CONNECTOR (BUS BUFFER ECU) BRANCH LINE)

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

(b) Disconnect the G80 option connector (bus buffer ECU).

HINT:

Disconnect any CAN compatible optional devices from the option connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
G80-2 (CAN+) - G80-1 (CAN-)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

*a	Front view of wire harness connector (to Option Connector (Bus Buffer ECU))

REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (OPTION CONNECTOR (BUS BUFFER ECU))

3.	CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G80-5 (GND) - Body ground	Cable disconnected from negative (-) battery terminal	Below 1 Ω

*a	Front view of wire harness connector (to Option Connector (Bus Buffer ECU))

(b) Reconnect the cable from the negative (-) battery terminal.

Standard Voltage:

Tester Connection	Condition	Specified Condition
G80-3 (R+B) - Body ground	Always	11 to 14 V

REPAIR OR REPLACE CAN COMPATIBLE OPTIONAL DEVICE

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

4.	CHECK FOR DTC

(a) Connect the Techstream to the DLC3.

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

(d) Enter the following menus: Body Electrical / Main Body / Utility / Initialization.

Body Electrical > Main Body > Utility

Tester Display
Initialization

(e) Enter the following menus: Body Electrical / Central Gateway / Utility / Initialization.

Body Electrical > Central Gateway > Utility

Tester Display
Initialization

(f) Enter the following menus: Body Electrical / Main Body / Clear DTCs.

Body Electrical > Main Body > Clear DTCs

(g) Enter the following menus: Body Electrical / Main Body / Trouble Codes.

Body Electrical > Main Body > Trouble Codes

Result	Proceed to
DTC U1117 is not output from main body ECU (multiplex network body ECU)	A
DTC U1117 is output from main body ECU (multiplex network body ECU)	B

END

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

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