Lexus ES: Check Bus 4 Line for Short to +B

Lexus ES (XZ10) Service Manual / Power Source & Network / Networking / Can Communication System (for Gasoline Model) / Check Bus 4 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when there is no resistance between terminal 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 7 (CA2L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Symptom	Trouble Area
There is no resistance between terminal 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 7 (CA2L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.	Short to +B in CAN main bus line Short to +B in CAN branch line Central gateway ECU (network gateway ECU) Tire pressure warning ECU and receiver Occupant detection ECU Steering sensor Rack and pinion power steering gear assembly Brake actuator assembly Absorber control ECU (w/ AVS System) Airbag ECU assembly No. 2 CAN junction connector No. 4 CAN junction connector No. 7 CAN junction connector

Symptom

Trouble Area

There is no resistance between terminal 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 7 (CA2L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Short to +B in CAN main bus line
Short to +B in CAN branch line
Central gateway ECU (network gateway ECU)
Tire pressure warning ECU and receiver
Occupant detection ECU
Steering sensor
Rack and pinion power steering gear assembly
Brake actuator assembly
Absorber control ECU
(w/ AVS System)
Airbag ECU assembly
No. 2 CAN junction connector
No. 4 CAN junction connector
No. 7 CAN junction connector

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.
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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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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 FOR SHORT TO +B IN CAN BUS LINE (NO. 7 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the N99 No. 7 CAN junction connector.

*1	DLC3	-	-
*a	Front view of wire harness connector (to No. 7 CAN Junction Connector)	*b	to Tire Pressure Warning ECU and Receiver
*c	to Occupant Detection ECU	*d	to Central Gateway ECU (Network Gateway ECU)
*e	to No. 4 CAN Junction Connector	*f	to Absorber Control ECU (w/ AVS System)

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
N99-1 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Tire pressure warning ECU and receiver
N99-7 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Tire pressure warning ECU and receiver
N99-2 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Occupant detection ECU
N99-8 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Occupant detection ECU
N99-3 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Central gateway ECU (network gateway ECU)
N99-9 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Central gateway ECU (network gateway ECU)
N99-4 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	No. 4 CAN junction connector
N99-10 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	No. 4 CAN junction connector
N99-5 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Absorber control ECU*
N99-11 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Absorber control ECU*

*: w/ AVS System

Result	Proceed to
OK	A
NG (Line to central gateway ECU (network gateway ECU))	B
NG (Line to No. 4 CAN junction connector)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 7 CAN JUNCTION CONNECTOR

GO TO STEP 3

GO TO STEP 6

2.	CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 7 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

(a) Disconnect the G66 central gateway ECU (network gateway ECU) connector.

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

DLC3

Front view of wire harness connector

(to No. 7 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection	Condition	Specified Condition
N99-3 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
N99-9 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 7 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

3.	CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR - NO. 7 CAN JUNCTION CONNECTOR)

(a) Disconnect the G99 No. 4 CAN junction connector.

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

DLC3

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

to No. 7 CAN Junction Connector

Standard Resistance:

Tester Connection	Condition	Specified Condition
G99-6 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G99-17 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - NO. 7 CAN JUNCTION CONNECTOR)

4.	CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR)

(a) Disconnect the G98 No. 4 CAN junction connector.

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

DLC3

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

to No. 2 CAN Junction Connector

to Steering Sensor

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
G98-6 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	No. 2 CAN junction connector
G98-17 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	No. 2 CAN junction connector
G98-7 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Steering sensor
G98-18 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Steering sensor

Result	Proceed to
OK	A
NG (Line to No. 2 CAN junction connector)	B
NG (Line to ECU or sensor)	C

REPLACE NO. 4 CAN JUNCTION CONNECTOR

GO TO STEP 6

5.	CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 2 CAN JUNCTION CONNECTOR)

(a) Disconnect the A69 No. 2 CAN junction connector.

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

*1	DLC3	-	-
*a	Front view of wire harness connector (to No. 2 CAN Junction Connector)	*b	to Brake Actuator Assembly
*c	to Airbag ECU Assembly	*d	to Rack and Pinion Power Steering Gear Assembly
*e	to No. 4 CAN Junction Connector	-	-

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
A69-1 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Brake actuator assembly
A69-11 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Brake actuator assembly
A69-2 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Airbag ECU assembly
A69-12 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Airbag ECU assembly
A69-4 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Rack and pinion power steering gear assembly
A69-14 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Rack and pinion power steering gear assembly
A69-5 (CANH) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	No. 4 CAN junction connector
A69-15 (CANL) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	No. 4 CAN junction connector

Result	Proceed to
OK	A
NG (Line to No. 4 CAN junction connector)	B
NG (Line to ECU or sensor)	C

REPLACE NO. 2 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR)

GO TO STEP 6

6.	CHECK FOR SHORT TO +B IN CAN BUS LINE (ECU OR SENSOR)

(a) Reconnect all wire harness connectors.

(b) Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the bus line shorted to +B is connected.

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DLC3

Component with harness connected

(Central Gateway ECU (Network Gateway ECU))

Standard Resistance:

Tester Connection	Condition	Specified Condition
G66-22 (CA2H) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G66-7 (CA2L) - G57-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

HINT:

If the resistance changes to 6 kΩ or higher when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.
If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short to +B in the wire harness and repair or replace the wire harness or connector if necessary.

REPLACE ECU OR SENSOR

REPAIR OR REPLACE HARNESS OR CONNECTOR

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Inspection

INSPECTION CAUTION / NOTICE / HINT NOTICE: When using a vise, place aluminum plates between the part and vise. When using a vise, do not overtighten it. PROCEDURE 1. INSPECT REAR DRIVE SHAFT ASSEMBLY (a) Check that there is no excessive play in the radial direction of the outboard joint.

Components

COMPONENTS ILLUSTRATION *A w/ Battery Insulator - - *1 BATTERY *2 NEGATIVE BATTERY TERMINAL *3 POSITIVE BATTERY TERMINAL *4 NO. 2 BATTERY CLAMP

Lexus ES: Check Bus 4 Line for Short to +B

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Check Bus 4 Lines for Short Circuit

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Inspection

Components