CAN COMMUNICATION SYSTEM Check Bus 2 Line for Short to GND

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and GND when there is no resistance between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom	Trouble Area
No resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.	Short to ground in CAN main bus line Short to ground in CAN branch line Central gateway ECU (network gateway ECU) ECM Engine stop and start ECU (w/ Stop and Start System) No. 3 CAN junction connector (w/ Stop and Start System)

WIRING DIAGRAM

w/o Stop and Start System

*1 Central Gateway ECU (Network Gateway ECU)

*1	Central Gateway ECU (Network Gateway ECU)

w/ Stop and Start System


*a	Engine Stop and Start ECU
*b	Central Gateway ECU (Network Gateway ECU)
*c	No. 3 CAN Junction Connector

CAUTION / NOTICE / HINT

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.

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Before measuring the resistance of the CAN bus, turn the ignition 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 ignition 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 blind spot monitor system on using the blind spot monitor main switch (ON/OFF switch), turn the cruise control main switch on, turn the LDA main switch on and then drive the vehicle at a speed of 60 km/h (37 mph) or more for approximately 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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Before replacing the ECM, refer to Service Bulletin.*1

*1: w/ Entry and Start System

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
w/o Stop and Start System	A
w/ Stop and Start System	B

CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR) Click here

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

Disconnect the cable from the negative (-) battery terminal.
Disconnect the central gateway ECU (network gateway ECU) connector.

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

DLC3

Front view of wire harness connector

(to Central Gateway ECU (Network Gateway ECU))

to ECM

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
F74-18 (CA4H) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	ECM
F74-17 (CA4L) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	ECM

Result

Result	Proceed to
OK (for LHD)	A
OK (for RHD)	B
NG	C

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

CHECK FOR SHORT TO GND IN CAN BUS LINE (ECM - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

Disconnect the A38 ECM connector.

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

DLC3

Front view of wire harness connector

(to Central Gateway ECU (Network Gateway ECU))

to ECM

Standard Resistance

Tester Connection	Condition	Specified Condition
F74-18 (CA4H) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
F74-17 (CA4L) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

Result

Result	Proceed to
OK (for 8NR-FTS)	A
OK (for 3ZR-FAE)	B
NG	C

REPLACE ECM Click here

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

CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR)

Disconnect the cable from the negative (-) battery terminal.
Disconnect the No. 3 CAN junction connector.

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

DLC3

Front view of wire harness connector

(to No. 3 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

to ECM

to Engine Stop and Start ECU

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
F113-1 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Central gateway ECU (network gateway ECU)
F113-12 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Central gateway ECU (network gateway ECU)
F113-4 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	ECM
F113-15 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	ECM
F113-6 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Engine stop and start ECU
F113-17 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Engine stop and start ECU

Result

Result	Proceed to
OK	A
NG (Line to central gateway ECU (network gateway ECU))	B
NG (Line to ECU or sensor)	C

REPLACE NO. 3 CAN JUNCTION CONNECTOR

CHECK FOR SHORT TO GND IN CAN BUS LINE (ECU OR SENSOR) Click here

CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

Disconnect the F74 central gateway ECU (network gateway ECU) connector.

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

DLC3

Front view of wire harness connector

(to No. 3 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance

Tester Connection	Condition	Specified Condition
F113-1 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
F113-12 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

Result

Result	Proceed to
OK (for LHD)	A
OK (for RHD)	B
NG	C

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

CHECK FOR SHORT TO GND 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 GND 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
F74-18 (CA4H) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
F74-17 (CA4L) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

Tech Tips

If the resistance changes to 200 Ω 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 ground 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