CAN COMMUNICATION SYSTEM Check Bus 2 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the CAN main bus lines and/or CAN branch lines when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom	Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of central gateway ECU (network gateway ECU) is below 54 Ω.	Short in CAN main bus lines Short in CAN branch lines Central gateway ECU (network gateway ECU) ECM Combination meter assembly Air conditioning amplifier assembly Engine stop and start ECU (w/ Stop and Start System) Power steering ECU assembly Certification ECU (smart key ECU assembly) Airbag sensor assembly Yaw rate sensor Main body ECU (multiplex network body ECU) Skid control ECU (brake actuator assembly) Stereo component equalizer assembly (w/ ASC System) Steering sensor Front steering control ECU (w/ VGRS System) No. 1 CAN junction connector No. 2 CAN junction connector

Symptom

Trouble Area

Resistance between terminals 18 (CA4H) and 17 (CA4L) of central gateway ECU (network gateway ECU) is below 54 Ω.

Short in CAN main bus lines
Short in CAN branch lines
Central gateway ECU (network gateway ECU)
ECM
Combination meter assembly
Air conditioning amplifier assembly
Engine stop and start ECU (w/ Stop and Start System)
Power steering ECU assembly
Certification ECU (smart key ECU assembly)
Airbag sensor assembly
Yaw rate sensor
Main body ECU (multiplex network body ECU)
Skid control ECU (brake actuator assembly)
Stereo component equalizer assembly (w/ ASC System)
Steering sensor
Front steering control ECU (w/ VGRS System)
No. 1 CAN junction connector
No. 2 CAN junction connector

WIRING DIAGRAM

Figure 1. for LHD:

Figure 2. for RHD:

CAUTION / NOTICE / HINT

CAUTION:

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

Note

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.

Click here
After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

DTC check procedure: Turn the ignition switch to ON 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.

Click here
Before replacing the ECM, main body ECU (multiplex network body ECU) or certification ECU (smart key ECU assembly), refer to Service Bulletin.

Tech Tips

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

CHECK VEHICLE TYPE

Check vehicle type.

Result

Result	Proceed to
for LHD	A
for RHD	B

CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY) Click here

CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY)

Disconnect the cable from the negative (-) battery terminal.
*a
Front view of wire harness connector

(to Combination Meter Assembly)

Disconnect the K3 combination meter assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
K3-29 (CANH) - K3-30 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Result	Proceed to
OK	A
NG (for 2GR-FKS Engine)	B
NG (for 8AR-FTS Engine)	C

REPLACE COMBINATION METER ASSEMBLY Click here

CHECK FOR SHORT IN CAN BUS LINES (ECM) Click here

CHECK FOR SHORT IN CAN BUS LINES (ECM)

Reconnect the K3 combination meter assembly connector.
*a
Front view of wire harness connector

(to ECM)

Disconnect the A108 ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A108-13 (CANH) - A108-26 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Result
OK
NG

REPLACE ECM Click here

GO TO STEP 5 Click here

CHECK FOR SHORT IN CAN BUS LINES (ECM)

Reconnect the K3 combination meter assembly connector.
*a
Front view of wire harness connector

(to ECM)

Disconnect the A91 ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A91-13 (CANH) - A91-26 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Result
OK
NG

REPLACE ECM Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)

Reconnect the A108*1 or A91*2 ECM connector.
- *1: for 2GR-FKS Engine
- *2: for 8AR-FTS Engine

Disconnect the K109 No. 1 CAN junction connector.

*a	Front view of wire harness connector (to No. 1 CAN Junction Connector)	*b	to No. 2 CAN Junction Connector
*c	to Combination Meter Assembly	*d	to Engine Stop and Start ECU (w/ Stop and Start System)
*e	to Central Gateway ECU (Network Gateway ECU)	*f	to Air Conditioning Amplifier Assembly
*g	to Stereo Component Equalizer Assembly (w/ ASC System)	*h	to Certification ECU (Smart Key ECU Assembly)
*i	to Power Steering ECU Assembly	-	-

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K109-1 (CANH) - K109-11 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 2 CAN junction connector
K109-2 (CANH) - K109-12 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Combination meter assembly
K109-3 (CANH) - K109-13 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Engine stop and start ECU*1
K109-4 (CANH) - K109-14 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Central gateway ECU (network gateway ECU)
K109-5 (CANH) - K109-15 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Air conditioning amplifier assembly
K109-6 (CANH) - K109-16 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Stereo component equalizer assembly*2
K109-7 (CANH) - K109-17 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Certification ECU (smart key ECU assembly)
K109-9 (CANH) - K109-19 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Power steering ECU assembly

*1: w/ Stop and Start System
*2: w/ ASC System

Result

Result	Proceed to
OK	A
NG (Line to No. 2 CAN junction connector)	B
NG (Line to combination meter assembly)	C
NG (Line to central gateway ECU (network gateway ECU))	D
NG (Line to ECU or sensor)	E

REPLACE NO. 1 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 1 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) Click here

GO TO STEP 14 Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)

Reconnect the K109 No. 1 CAN junction connector.

Disconnect the K110 No. 2 CAN junction connector.

*a	Front view of wire harness connector (to No. 2 CAN Junction Connector)	*b	to No. 1 CAN Junction Connector
*c	to Main Body ECU (Multiplex Network Body ECU)	*d	to ECM
*e	to Airbag Sensor Assembly	*f	to Yaw Rate Sensor
*g	to Steering Sensor	*h	to Skid Control ECU (Brake Actuator Assembly)

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K110-1 (CANH) - K110-11 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 1 CAN junction connector
K110-2 (CANH) - K110-12 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Main body ECU (multiplex network body ECU)
K110-3 (CANH) - K110-13 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	ECM
K110-5 (CANH) - K110-15 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Airbag sensor assembly
K110-6 (CANH) - K110-16 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Yaw rate sensor
K110-9 (CANH) - K110-19 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Steering sensor
K110-10 (CANH) - K110-20 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Skid control ECU (brake actuator assembly)

Result

Result	Proceed to
OK	A
NG (Line to No. 1 CAN junction connector)	B
NG (Line to ECM)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 2 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (ECM - NO. 2 CAN JUNCTION CONNECTOR)

GO TO STEP 14 Click here

CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

Reconnect the K109 No. 1 CAN junction connector.
*a
Front view of wire harness connector

(to Central Gateway ECU (Network Gateway ECU))

Disconnect the K141 central gateway ECU (network gateway ECU) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
K141-18 (CA4H) - K141-17 (CA4L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Result

Result
OK
NG

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY)

Disconnect the cable from the negative (-) battery terminal.
*a
Front view of wire harness connector

(to Combination Meter Assembly)

Disconnect the K3 combination meter assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
K3-29 (CANH) - K3-30 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Result	Proceed to
OK	A
NG (for 2GR-FKS Engine)	B
NG (for 8AR-FTS Engine)	C

REPLACE COMBINATION METER ASSEMBLY Click here

CHECK FOR SHORT IN CAN BUS LINES (ECM) Click here

CHECK FOR SHORT IN CAN BUS LINES (ECM)

Reconnect the K3 combination meter assembly connector.
*a
Front view of wire harness connector

(to ECM)

Disconnect the A108 ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A108-13 (CANH) - A108-26 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Result
OK
NG

REPLACE ECM Click here

GO TO STEP 11 Click here

CHECK FOR SHORT IN CAN BUS LINES (ECM)

Reconnect the K3 combination meter assembly connector.
*a
Front view of wire harness connector

(to ECM)

Disconnect the A91 ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A91-13 (CANH) - A91-26 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Result
OK
NG

REPLACE ECM Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)

Reconnect the A108*1 or A91*2 ECM connector.
- *1: for 2GR-FKS Engine
- *2: for 8AR-FTS Engine

Disconnect the K109 No. 1 CAN junction connector.

*a	Front view of wire harness connector (to No. 1 CAN Junction Connector)	*b	to No. 2 CAN Junction Connector
*c	to Combination Meter Assembly	*d	to Engine Stop and Start ECU (w/ Stop and Start System)
*e	to Airbag Sensor Assembly	*f	to Yaw Rate Sensor
*g	to Skid Control ECU (Brake Actuator Assembly)	*h	to Steering Sensor

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K109-1 (CANH) - K109-11 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 2 CAN junction connector
K109-2 (CANH) - K109-12 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Combination meter assembly
K109-3 (CANH) - K109-13 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Engine stop and start ECU*
K109-4 (CANH) - K109-14 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Airbag sensor assembly
K109-5 (CANH) - K109-15 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Yaw rate sensor
K109-6 (CANH) - K109-16 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Skid control ECU (brake actuator assembly)
K109-7 (CANH) - K109-17 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Steering sensor

*: w/ Stop and Start System

Result

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

REPLACE NO. 1 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 1 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS LINES (ECU, SENSOR) Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)

Reconnect the K109 No. 1 CAN junction connector.

Disconnect the K110 No. 2 CAN junction connector.

*a	Front view of wire harness connector (to No. 2 CAN Junction Connector)	*b	to No. 1 CAN Junction Connector
*c	to Main Body ECU (Multiplex Network Body ECU)	*d	to ECM
*e	to Central Gateway ECU (Network Gateway ECU)	*f	to Air Conditioning Amplifier Assembly
*g	to Front Steering Control ECU (w/ VGRS System)	*h	to Certification ECU (Smart Key ECU Assembly)
*i	to Stereo Component Equalizer Assembly (w/ ASC System)	*j	to Power Steering ECU Assembly

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K110-1 (CANH) - K110-11 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 1 CAN junction connector
K110-2 (CANH) - K110-12 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Main body ECU (multiplex network body ECU)
K110-3 (CANH) - K110-13 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	ECM
K110-5 (CANH) - K110-15 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Central gateway ECU (network gateway ECU)
K110-6 (CANH) - K110-16 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Air conditioning amplifier assembly
K110-7 (CANH) - K110-17 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Front steering control ECU*1
K110-8 (CANH) - K110-18 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Certification ECU (smart key ECU assembly)
K110-9 (CANH) - K110-19 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Stereo component equalizer assembly*2
K110-10 (CANH) - K110-20 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Power steering ECU assembly

*1: w/ VGRS System
*2: w/ ASC System

Result

Result	Proceed to
OK	A
NG (Line to No. 1 CAN junction connector)	B
NG (Line to ECM)	C
NG (Line to central gateway ECU (network gateway ECU))	D
NG (Line to ECU or sensor)	E

REPLACE NO. 2 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (ECM - NO. 2 CAN JUNCTION CONNECTOR)

GO TO STEP 14 Click here

CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

Reconnect the K110 No. 2 CAN junction connector.
*a
Front view of wire harness connector

(to Central Gateway ECU (Network Gateway ECU))

Disconnect the K141 central gateway ECU (network gateway ECU) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
K141-18 (CA4H) - K141-17 (CA4L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Result

Result
OK
NG

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

CHECK FOR SHORT IN CAN BUS LINES (ECU, SENSOR)

Reconnect all wire harness connectors.
Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited branch line is connected.

Click here

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

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

Standard Resistance

Tester Connection	Condition	Specified Condition
K141-18 (CA4H) - K141-17 (CA4L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Tech Tips

If the resistance becomes normal (between 54 and 69 Ω) when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.

Result

Result
OK
NG

REPLACE CORRESPONDING ECU OR SENSOR

REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINES OR CONNECTOR