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) Hybrid vehicle control ECU assembly Blind spot monitor sensor LH (w/ Blind Spot Monitor System) Absorber control ECU (w/ AVS System) Driving support ECU assembly (w/ Lexus Safety System +) Millimeter wave radar sensor assembly (w/ Lexus Safety System +) Forward recognition camera (w/ Lexus Safety System +) Clearance warning ECU assembly (w/ LEXUS Parking Assist-sensor System) No. 10 CAN junction connector No. 12 CAN junction connector No. 13 CAN junction connector

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)
Hybrid vehicle control ECU assembly
Blind spot monitor sensor LH

(w/ Blind Spot Monitor System)
Absorber control ECU

(w/ AVS System)
Driving support ECU assembly

(w/ Lexus Safety System +)
Millimeter wave radar sensor assembly

(w/ Lexus Safety System +)
Forward recognition camera

(w/ Lexus Safety System +)
Clearance warning ECU assembly

(w/ LEXUS Parking Assist-sensor System)
No. 10 CAN junction connector
No. 12 CAN junction connector
No. 13 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

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 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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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 (NO. 13 CAN JUNCTION CONNECTOR) Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 13 CAN JUNCTION CONNECTOR)

Disconnect the cable from the negative (-) auxiliary battery terminal.
Disconnect the K151, K152, K153, K154, K155 and K159 No. 13 CAN junction connectors.

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

*a	Rear view of wire harness connector (to No. 13 CAN Junction Connector)	*b	to No. 12 CAN Junction Connector
*c	to Forward Recognition Camera (w/ Lexus Safety System +)	*d	to Millimeter Wave Radar Sensor Assembly (w/ Lexus Safety System +)
*e	to Clearance Warning ECU Assembly (w/ LEXUS Parking Assist-sensor System)	*f	to No. 10 CAN Junction Connector
*g	to Driving Support ECU Assembly (w/ Lexus Safety System +)	-	-

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K151-1 (CANH) - K151-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 12 CAN junction connector
K152-1 (CANH) - K152-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Forward recognition camera*1
K153-1 (CANH) - K153-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Millimeter wave radar sensor assembly*1
K154-1 (CANH) - K154-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Clearance warning ECU assembly*2
K155-1 (CANH) - K155-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 10 CAN junction connector
K159-1 (CANH) - K159-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Driving support ECU assembly*1

*1: w/ Lexus Safety System +
*2: w/ LEXUS Parking Assist-sensor System

Result

Result	Proceed to
OK	A
NG (Line to No. 10 CAN junction connector)	B
NG (Line to No. 12 CAN junction connector)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 13 CAN JUNCTION CONNECTOR

CHECK FOR SHORT IN CAN BUS LINES (NO. 12 CAN JUNCTION CONNECTOR) Click here

GO TO STEP 12 Click here

CHECK FOR SHORT IN CAN BUS LINES (NO. 10 CAN JUNCTION CONNECTOR)

Reconnect the K151, K152, K153, K154, K155 and K159 No. 13 CAN junction connectors.
Disconnect the Q68 No. 10 CAN junction connector.

*a	Front view of wire harness connector (to No. 10 CAN Junction Connector)
*b	to No. 13 CAN Junction Connector
*c	to Central Gateway ECU (Network Gateway ECU)
*d	to Blind Spot Monitor Sensor LH (w/ Blind Spot Monitor System)

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
Q68-3 (CANH) - Q68-9 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 13 CAN junction connector
Q68-4 (CANH) - Q68-10 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Central gateway ECU (network gateway ECU)
Q68-5 (CANH) - Q68-11 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Blind spot monitor sensor LH*

*: w/ Blind Spot Monitor System

Result

Result	Proceed to
OK	A
NG (Line to No. 13 CAN junction connector)	B
NG (Line to central gateway ECU (network gateway ECU))	C
NG (Line to ECU or sensor)	D

REPLACE NO. 10 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 10 CAN JUNCTION CONNECTOR - NO. 13 CAN JUNCTION CONNECTOR)

GO TO STEP 12 Click here

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

Reconnect the Q68 No. 10 CAN junction connector.
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
K146-15 (CA5H) - K146-16 (CA5L)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Result

Result
OK
NG

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) - NO. 10 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS LINES (NO. 12 CAN JUNCTION CONNECTOR)

Reconnect the K151, K152, K153, K154, K155 and K159 No. 13 CAN junction connectors.
Disconnect the K147, K148 and K149 No. 12 CAN junction connectors.

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

Rear view of wire harness connector

(to No. 12 CAN Junction Connector)

to Hybrid Vehicle Control ECU Assembly

to No. 13 CAN Junction Connector

to Absorber Control ECU

(w/ AVS System)

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K147-1 (CANH) - K147-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Hybrid vehicle control ECU assembly
K148-1 (CANH) - K148-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 13 CAN junction connector
K149-1 (CANH) - K149-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Absorber control ECU*

*: w/ AVS System

Result

Result	Proceed to
OK	A
NG (Line to hybrid vehicle control ECU assembly)	B
NG (Line to No. 13 CAN junction connector)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 12 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 12 CAN JUNCTION CONNECTOR - NO. 13 CAN JUNCTION CONNECTOR)

GO TO STEP 12 Click here

CHECK FOR SHORT IN CAN BUS LINES (HYBRID VEHICLE CONTROL ECU ASSEMBLY)

Reconnect the K147, K148 and K149 No. 12 CAN junction connectors.
Disconnect the K141 hybrid vehicle control ECU assembly connector.

*a	Front view of wire harness connector (to Hybrid Vehicle Control ECU Assembly)

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

Standard Resistance

Tester Connection	Condition	Specified Condition
K141-34 (CA2H) - K141-35 (CA2L)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Result

Result
OK
NG

REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (HYBRID VEHICLE CONTROL ECU ASSEMBLY - NO. 12 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS LINES (NO. 13 CAN JUNCTION CONNECTOR)

Disconnect the cable from the negative (-) auxiliary battery terminal.
Disconnect the K151, K152, K153, K154 and K155 No. 13 CAN junction connectors.

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

Rear view of wire harness connector

(to No. 13 CAN Junction Connector)

to No. 12 CAN Junction Connector

to Forward Recognition Camera

(w/ Lexus Safety System +)

to Millimeter Wave Radar Sensor Assembly

(w/ Lexus Safety System +)

to Clearance Warning ECU Assembly

(w/ LEXUS Parking Assist-sensor System)

to No. 10 CAN Junction Connector

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K151-1 (CANH) - K151-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 12 CAN junction connector
K152-1 (CANH) - K152-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Forward recognition camera*1
K153-1 (CANH) - K153-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Millimeter wave radar sensor assembly*1
K154-1 (CANH) - K154-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Clearance warning ECU assembly*2
K155-1 (CANH) - K155-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 10 CAN junction connector

*1: w/ Lexus Safety System +
*2: w/ LEXUS Parking Assist-sensor System

Result

Result	Proceed to
OK	A
NG (Line to No. 10 CAN junction connector)	B
NG (Line to No. 12 CAN junction connector)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 13 CAN JUNCTION CONNECTOR

CHECK FOR SHORT IN CAN BUS LINES (NO. 12 CAN JUNCTION CONNECTOR) Click here

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

CHECK FOR SHORT IN CAN BUS LINES (NO. 10 CAN JUNCTION CONNECTOR)

Reconnect the K151, K152, K153, K154 and K155 No. 13 CAN junction connectors.
Disconnect the Q68 No. 10 CAN junction connector.

*a	Front view of wire harness connector (to No. 10 CAN Junction Connector)
*b	to No. 13 CAN Junction Connector
*c	to Hybrid Vehicle Control ECU Assembly
*d	to Blind Spot Monitor Sensor LH (w/ Blind Spot Monitor System)

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
Q68-3 (CANH) - Q68-9 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 13 CAN junction connector
Q68-4 (CANH) - Q68-10 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Hybrid vehicle control ECU assembly
Q68-5 (CANH) - Q68-11 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Blind spot monitor sensor LH*

*: w/ Blind Spot Monitor System

Result

Result	Proceed to
OK	A
NG (Line to No. 13 CAN junction connector)	B
NG (Line to hybrid vehicle control ECU assembly)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 10 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 10 CAN JUNCTION CONNECTOR - NO. 13 CAN JUNCTION CONNECTOR)

GO TO STEP 12 Click here

CHECK FOR SHORT IN CAN BUS LINES (HYBRID VEHICLE CONTROL ECU ASSEMBLY)

Reconnect the Q68 No. 10 CAN junction connector.
Disconnect the K141 hybrid vehicle control ECU assembly connector.

*a	Front view of wire harness connector (to Hybrid Vehicle Control ECU Assembly)

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

Standard Resistance

Tester Connection	Condition	Specified Condition
K141-34 (CA2H) - K141-35 (CA2L)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Result

Result
OK
NG

REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (HYBRID VEHICLE CONTROL ECU ASSEMBLY - NO. 10 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS LINES (NO. 12 CAN JUNCTION CONNECTOR)

Reconnect the K151, K152, K153, K154 and K155 No. 13 CAN junction connectors.
Disconnect the K147, K148, K149 and K150 No. 12 CAN junction connectors.

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

Rear view of wire harness connector

(to No. 12 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

to No. 13 CAN Junction Connector

to Absorber Control ECU

(w/ AVS System)

to Driving Support ECU Assembly

(w/ Lexus Safety System +)

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K147-1 (CANH) - K147-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Central gateway ECU (network gateway ECU)
K148-1 (CANH) - K148-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 13 CAN junction connector
K149-1 (CANH) - K149-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Absorber control ECU*1
K150-1 (CANH) - K150-2 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Driving support ECU assembly*2

*1: w/ AVS System
*2: w/ Lexus Safety System +

Result

Result	Proceed to
OK	A
NG (Line to central gateway ECU (network gateway ECU))	B
NG (Line to No. 13 CAN junction connector)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 12 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 12 CAN JUNCTION CONNECTOR - NO. 13 CAN JUNCTION CONNECTOR)

GO TO STEP 12 Click here

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

Reconnect the K147, K148, K149 and K150 No. 12 CAN junction connectors.
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
K146-15 (CA5H) - K146-16 (CA5L)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Result

Result
OK
NG

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) - NO. 12 CAN JUNCTION CONNECTOR)

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
K146-15 (CA5H) - K146-16 (CA5L)	Cable disconnected from negative (-) auxiliary 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