CAN COMMUNICATION SYSTEM Check Bus 5 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 15 (CA5H) and 16 (CA5L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom	Trouble Area
Resistance between terminals 15 (CA5H) and 16 (CA5L) of the 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) Headlight ECU sub-assembly LH (w/ Automatic Headlight Beam Level Control System) Headlight ECU sub-assembly RH (w/ Automatic Headlight Beam Level Control System) Outer mirror control ECU assembly (for driver side) (w/ Seat Position Memory System) Outer mirror control ECU assembly (for front passenger side) (w/ Seat Position Memory System) Position control ECU assembly RH (w/ Seat Position Memory System) Multiplex tilt and telescopic ECU (w/ Power Tilt and Power Telescopic System) Air conditioning amplifier assembly Certification ECU (smart key ECU assembly) (w/ Smart Entry and Start System) Main body ECU (multiplex network body ECU) Combination meter assembly Meter mirror sub-assembly (w/ Headup Display System) No. 3 CAN junction connector No. 1 junction connector No. 2 junction connector No. 5 junction connector (for RHD) No. 6 junction connector (for LHD)

Symptom

Trouble Area

Resistance between terminals 15 (CA5H) and 16 (CA5L) of the 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)
Headlight ECU sub-assembly LH

(w/ Automatic Headlight Beam Level Control System)
Headlight ECU sub-assembly RH

(w/ Automatic Headlight Beam Level Control System)
Outer mirror control ECU assembly (for driver side)

(w/ Seat Position Memory System)
Outer mirror control ECU assembly (for front passenger side)

(w/ Seat Position Memory System)
Position control ECU assembly RH

(w/ Seat Position Memory System)
Multiplex tilt and telescopic ECU

(w/ Power Tilt and Power Telescopic System)
Air conditioning amplifier assembly
Certification ECU (smart key ECU assembly)

(w/ Smart Entry and Start System)
Main body ECU (multiplex network body ECU)
Combination meter assembly
Meter mirror sub-assembly

(w/ Headup Display System)
No. 3 CAN junction connector
No. 1 junction connector
No. 2 junction connector
No. 5 junction connector

(for RHD)
No. 6 junction connector

(for LHD)

WIRING DIAGRAM

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 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.

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 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 FOR SHORT IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR)

Disconnect the cable from the negative (-) battery terminal.
Disconnect the K126 No. 3 CAN junction connector.

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

*a	Front view of wire harness connector (to No. 3 CAN Junction Connector)	*b	to No. 1 Junction Connector
*c	to Certification ECU (Smart Key ECU Assembly) (w/ Smart Entry and Start System)	*d	to Combination Meter Assembly
*e	to Main Body ECU (Multiplex Network Body ECU)	*f	to Air Conditioning Amplifier Assembly
*g	to Headlight ECU Sub-assembly LH (w/ Automatic Headlight Beam Level Control System)	*h	to Meter Mirror Sub-assembly (w/ Headup Display System)
*i	to Multiplex Tilt and Telescopic ECU (w/ Power Tilt and Power Telescopic System)	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K126-3 (CANH) - K126-14 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 1 junction connector
K126-4 (CANH) - K126-15 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Certification ECU (smart key ECU assembly)*1
K126-5 (CANH) - K126-16 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Combination meter assembly
K126-6 (CANH) - K126-17 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Main body ECU (multiplex network body ECU)
K126-7 (CANH) - K126-18 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Air conditioning amplifier assembly
K126-8 (CANH) - K126-19 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Headlight ECU sub-assembly LH*2
K126-9 (CANH) - K126-20 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Meter mirror sub-assembly*3
K126-10 (CANH) - K126-21 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Multiplex tilt and telescopic ECU*4

*1: w/ Smart Entry and Start System
*2: w/ Automatic Headlight Beam Level Control System
*3: w/ Headup Display System
*4: w/ Power Tilt and Power Telescopic System

Result

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

REPLACE NO. 3 CAN JUNCTION CONNECTOR

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

GO TO STEP 8 Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR - COMBINATION METER ASSEMBLY)

Disconnect the K21 combination meter assembly connector.

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

Front view of wire harness connector

(to No. 3 CAN Junction Connector)

to Combination Meter Assembly

Standard Resistance

Tester Connection	Condition	Specified Condition
K126-5 (CANH) - K126-16 (CANL)	Cable disconnected from negative (-) battery terminal	1 MΩ or higher

Result

Result
OK
NG

REPLACE COMBINATION METER ASSEMBLY Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - COMBINATION METER ASSEMBLY)

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

Reconnect the K126 No. 3 CAN junction connector.
Disconnect the R94 No. 1 junction connector.

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

Front view of wire harness connector

(to No. 1 Junction Connector)

to Outer Mirror Control ECU Assembly (for Front Passenger Side)

(w/ Seat Position Memory System)

to No. 3 CAN Junction Connector

to No. 5 Junction Connector

(for RHD)

to No. 6 Junction Connector

(for LHD)

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
R94-1 (CANH) - R94-12 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Outer mirror control ECU assembly (for front passenger side)*1
R94-3 (CANH) - R94-14 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 3 CAN junction connector
R94-4 (CANH) - R94-15 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 5 junction connector*2
R94-4 (CANH) - R94-15 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 6 junction connector*3

*1: w/ Seat Position Memory System
*2: for RHD
*3: for LHD

Result

Result	Proceed to
OK	A
NG (Line to No. 3 CAN junction connector)	B
NG (Line to No. 5 junction connector (for RHD))	C
NG (Line to No. 6 junction connector (for LHD))	D
NG (Line to ECU or sensor)	E

REPLACE NO. 1 JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 1 JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS LINES (NO. 6 JUNCTION CONNECTOR) Click here

GO TO STEP 8 Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 5 JUNCTION CONNECTOR)

Reconnect the R94 No. 1 junction connector.
Disconnect the R100 No. 5 junction connector.

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

Front view of wire harness connector

(to No. 5 Junction Connector)

to No. 2 Junction Connector

to No. 1 Junction Connector

to Position Control ECU Assembly RH

(w/ Seat Position Memory System)

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
R100-5 (CANH) - R100-16 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 2 junction connector
R100-6 (CANH) - R100-17 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 1 junction connector
R100-7 (CANH) - R100-18 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Position control ECU assembly RH*

*: w/ Seat Position Memory System

Result

Result	Proceed to
OK	A
NG (Line to No. 1 junction connector)	B
NG (Line to No. 2 junction connector)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 5 JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 5 JUNCTION CONNECTOR - NO. 1 JUNCTION CONNECTOR)

GO TO STEP 6 Click here

GO TO STEP 8 Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 6 JUNCTION CONNECTOR)

Reconnect the R94 No. 1 junction connector.
Disconnect the R101 No. 6 junction connector.

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

Front view of wire harness connector

(to No. 6 Junction Connector)

to No. 2 Junction Connector

to No. 1 Junction Connector

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
R101-1 (CANH) - R101-12 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 2 junction connector
R101-2 (CANH) - R101-13 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 1 junction connector

Result

Result	Proceed to
OK	A
NG (Line to No. 1 junction connector)	B
NG (Line to No. 2 junction connector)	C

REPLACE NO. 6 JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 6 JUNCTION CONNECTOR - NO. 1 JUNCTION CONNECTOR)

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

Reconnect the R100 No. 5 junction connector or R101 No. 6 junction connector.
Disconnect the R97 No. 2 junction connector.

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

Front view of wire harness connector

(to No. 2 Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

to No. 5 Junction Connector

(for RHD)

to No. 6 Junction Connector

(for LHD)

to Outer Mirror Control ECU Assembly (for Driver Side)

(w/ Seat Position Memory System)

to Headlight ECU Sub-assembly RH

(w/ Automatic Headlight Beam Level Control System)

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
R97-1 (CANH) - R97-12 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Central gateway ECU (network gateway ECU)
R97-2 (CANH) - R97-13 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 5 junction connector*1
R97-2 (CANH) - R97-13 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 6 junction connector*2
R97-3 (CANH) - R97-14 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Outer mirror control ECU assembly (for driver side)*3
R97-5 (CANH) - R97-16 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Headlight ECU sub-assembly RH*4

*1: for RHD
*2: for LHD
*3: w/ Seat Position Memory System
*4: w/ Automatic Headlight Beam Level Control System

Result

Result	Proceed to
OK	A
NG (Line to No. 5 junction connector (for RHD))	B
NG (Line to No. 6 junction connector (for LHD))	C
NG (Line to central gateway ECU (network gateway ECU))	D
NG (Line to ECU or sensor)	E

REPLACE NO. 2 JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 JUNCTION CONNECTOR - NO. 5 JUNCTION CONNECTOR)

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 JUNCTION CONNECTOR - NO. 6 JUNCTION CONNECTOR)

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

CHECK FOR SHORT IN CAN BUS LINES (NO. 2 JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

Disconnect the K76 central gateway ECU (network gateway ECU) connector.

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

Front view of wire harness connector

(to No. 2 Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance

Tester Connection	Condition	Specified Condition
R97-1 (CANH) - R97-12 (CANL)	Cable disconnected from negative (-) battery terminal	1 MΩ or higher

Result

Result
OK
NG

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

CHECK FOR SHORT IN CAN BUS LINES (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 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
K76-15 (CA5H) - K76-16 (CA5L)	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.
If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short 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