CAN COMMUNICATION SYSTEM Check Bus 2 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Symptom	Trouble Area
No resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) 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) ECM Combination meter assembly Power steering ECU assembly Main body ECU (multiplex network body ECU) Steering sensor Airbag sensor assembly Skid control ECU assembly Air conditioning amplifier assembly Certification ECU (smart key ECU assembly) Stereo component equalizer assembly (w/ ASC System) Yaw rate sensor Hybrid vehicle control ECU assembly No. 1 CAN junction connector No. 2 CAN junction connector

Symptom

Trouble Area

No resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) 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)
ECM
Combination meter assembly
Power steering ECU assembly
Main body ECU (multiplex network body ECU)
Steering sensor
Airbag sensor assembly
Skid control ECU assembly
Air conditioning amplifier assembly
Certification ECU (smart key ECU assembly)
Stereo component equalizer assembly

(w/ ASC System)
Yaw rate sensor
Hybrid vehicle control ECU assembly
No. 1 CAN junction connector
No. 2 CAN junction connector

WIRING DIAGRAM

Figure 1. for LHD

Figure 2. for RHD

CAUTION / NOTICE / HINT

Note

Before measuring the resistance of the CAN bus, turn the power 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 (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

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

DTC check procedure: Turn the power switch on (IG) and wait at least 60 seconds. Turn the lane departure alert main switch on and then drive the vehicle at a speed of 36 km/h (22 mph) or more for 300 seconds 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
If the main body ECU (multiplex network body ECU) is replaced, 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 TO +B IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR) Click here

CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR)

Disconnect the cable from the negative (-) auxiliary battery terminal.
Disconnect the K109 No. 1 CAN junction connector.

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

*1	DLC3	-	-
*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 Central Gateway ECU (Network Gateway ECU)
*e	to Air Conditioning Amplifier Assembly	*f	to Stereo Component Equalizer Assembly (w/ ASC System)
*g	to Certification ECU (Smart Key ECU Assembly)	*h	to Hybrid Vehicle Control ECU Assembly
*i	to Power Steering ECU Assembly	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K109-1 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	No. 2 CAN junction connector
K109-11 (CANL) - K9-16 (BAT)		6 kΩ or higher	No. 2 CAN junction connector
K109-2 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Combination meter assembly
K109-12 (CANL) - K9-16 (BAT)		6 kΩ or higher	Combination meter assembly
K109-4 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Central gateway ECU (network gateway ECU)
K109-14 (CANL) - K9-16 (BAT)		6 kΩ or higher	Central gateway ECU (network gateway ECU)
K109-5 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Air conditioning amplifier assembly
K109-15 (CANL) - K9-16 (BAT)		6 kΩ or higher	Air conditioning amplifier assembly
K109-6 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Stereo component equalizer assembly*
K109-16 (CANL) - K9-16 (BAT)		6 kΩ or higher	Stereo component equalizer assembly*
K109-7 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Certification ECU (smart key ECU assembly)
K109-17 (CANL) - K9-16 (BAT)		6 kΩ or higher	Certification ECU (smart key ECU assembly)
K109-8 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Hybrid vehicle control ECU assembly
K109-18 (CANL) - K9-16 (BAT)		6 kΩ or higher	Hybrid vehicle control ECU assembly
K109-9 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Power steering ECU assembly
K109-19 (CANL) - K9-16 (BAT)		6 kΩ or higher	Power steering ECU assembly

*: w/ ASC System

Result

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

REPLACE NO. 1 CAN JUNCTION CONNECTOR

GO TO STEP 7 Click here

CHECK FOR SHORT TO +B IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) Click here

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

Reconnect the K109 No. 1 CAN junction connector.
Disconnect the K110 No. 2 CAN junction connector.

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 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 Assembly

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K110-1 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	No. 1 CAN junction connector
K110-11 (CANL) - K9-16 (BAT)		6 kΩ or higher	No. 1 CAN junction connector
K110-2 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Main body ECU (multiplex network body ECU)
K110-12 (CANL) - K9-16 (BAT)		6 kΩ or higher	Main body ECU (multiplex network body ECU)
K110-3 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	ECM
K110-13 (CANL) - K9-16 (BAT)		6 kΩ or higher	ECM
K110-5 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Airbag sensor assembly
K110-15 (CANL) - K9-16 (BAT)		6 kΩ or higher	Airbag sensor assembly
K110-6 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Yaw rate sensor
K110-16 (CANL) - K9-16 (BAT)		6 kΩ or higher	Yaw rate sensor
K110-9 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Steering sensor
K110-19 (CANL) - K9-16 (BAT)		6 kΩ or higher	Steering sensor
K110-10 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Skid Control ECU Assembly
K110-20 (CANL) - K9-16 (BAT)		6 kΩ or higher	Skid Control ECU Assembly

Result

Result	Proceed to
OK	A
NG (Line to No. 1 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. 1 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)

GO TO STEP 7 Click here

CHECK FOR SHORT TO +B IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

Disconnect the K146 central gateway ECU (network gateway ECU) connector.

*a	Front view of wire harness connector (to 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
K146-18 (CA4H) - K146-1 (BATT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher
K146-17 (CA4L) - K146-1 (BATT)		6 kΩ or higher

Result

Result
OK
NG

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR)

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

Disconnect the K109 No. 1 CAN junction connector.

*1	DLC3	-	-
*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 Airbag Sensor Assembly
*e	to Yaw Rate Sensor	*f	to Skid Control ECU Assembly
*g	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) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	No. 2 CAN junction connector
K109-11 (CANL) - K9-16 (BAT)		6 kΩ or higher	No. 2 CAN junction connector
K109-2 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Combination meter assembly
K109-12 (CANL) - K9-16 (BAT)		6 kΩ or higher	Combination meter assembly
K109-4 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Airbag sensor assembly
K109-14 (CANL) - K9-16 (BAT)		6 kΩ or higher	Airbag sensor assembly
K109-5 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Yaw rate sensor
K109-15 (CANL) - K9-16 (BAT)		6 kΩ or higher	Yaw rate sensor
K109-6 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Skid control ECU assembly
K109-16 (CANL) - K9-16 (BAT)		6 kΩ or higher	Skid control ECU assembly
K109-7 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Steering sensor
K109-17 (CANL) - K9-16 (BAT)		6 kΩ or higher	Steering sensor

Result

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

REPLACE NO. 1 CAN JUNCTION CONNECTOR

GO TO STEP 7 Click here

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

Reconnect the K109 No. 1 CAN junction connector.

Disconnect the K110 No. 2 CAN junction connector.

*1	DLC3	-	-
*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 Hybrid Vehicle Control ECU Assembly	*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) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	No. 1 CAN junction connector
K110-11 (CANL) - K9-16 (BAT)		6 kΩ or higher	No. 1 CAN junction connector
K110-2 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Main body ECU (multiplex network body ECU)
K110-12 (CANL) - K9-16 (BAT)		6 kΩ or higher	Main body ECU (multiplex network body ECU)
K110-3 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	ECM
K110-13 (CANL) - K9-16 (BAT)		6 kΩ or higher	ECM
K110-5 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Central gateway ECU (network gateway ECU)
K110-15 (CANL) - K9-16 (BAT)		6 kΩ or higher	Central gateway ECU (network gateway ECU)
K110-6 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Air conditioning amplifier assembly
K110-16 (CANL) - K9-16 (BAT)		6 kΩ or higher	Air conditioning amplifier assembly
K110-7 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Hybrid vehicle control ECU assembly
K110-17 (CANL) - K9-16 (BAT)		6 kΩ or higher	Hybrid vehicle control ECU assembly
K110-8 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Certification ECU (smart key ECU assembly)
K110-18 (CANL) - K9-16 (BAT)		6 kΩ or higher	Certification ECU (smart key ECU assembly)
K110-9 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Stereo component equalizer assembly*
K110-19 (CANL) - K9-16 (BAT)		6 kΩ or higher	Stereo component equalizer assembly*
K110-10 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Power steering ECU assembly
K110-20 (CANL) - K9-16 (BAT)		6 kΩ or higher	Power steering ECU assembly

*: w/ ASC System

Result

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

REPLACE NO. 2 CAN JUNCTION CONNECTOR

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

CHECK FOR SHORT TO +B IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) Click here

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

Reconnect all wire harness connectors.
Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the bus line shorted to +B is connected.

Click here

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

DLC3

Component with harness connected

(Central Gateway ECU (Network Gateway ECU))

Standard Resistance

Tester Connection	Condition	Specified Condition
K146-18 (CA4H) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher
K146-17 (CA4L) - K9-16 (BAT)		6 kΩ or higher

Tech Tips

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.

Result

Result
OK
NG

REPLACE ECU OR SENSOR

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK FOR SHORT TO +B IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

Disconnect the K146 central gateway ECU (network gateway ECU) connector.

*a	Front view of wire harness connector (to 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
K146-18 (CA4H) - K146-1 (BATT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher
K146-17 (CA4L) - K146-1 (BATT)		6 kΩ or higher

Result

Result
OK
NG

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))