Toyota Avalon (XX50): Check Bus 1 Lines for Short Circuit

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Power Source, Network / Networking / Can Communication System(for Hv Model) / Check Bus 1 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 23 (CA1H) and 8 (CA1L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom	Trouble Area
Resistance between terminals 23 (CA1H) and 8 (CA1L) 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) Forward recognition camera Millimeter wave radar sensor assembly Swing grille actuator assembly Blind spot monitor sensor RH Television camera assembly Clearance warning ECU assembly (w/ Intelligent Clearance Sonar System) Parking assist ECU (w/ Panoramic View Monitor System) Driving support ECU assembly No. 1 CAN junction connector No. 7 CAN junction connector

Symptom

Trouble Area

Resistance between terminals 23 (CA1H) and 8 (CA1L) 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)
Forward recognition camera
Millimeter wave radar sensor assembly
Swing grille actuator assembly
Blind spot monitor sensor RH
Television camera assembly
Clearance warning ECU assembly
(w/ Intelligent Clearance Sonar System)
Parking assist ECU
(w/ Panoramic View Monitor System)
Driving support ECU assembly
No. 1 CAN junction connector
No. 7 CAN junction connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION:

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

NOTICE:

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 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.
Click here
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.
Click here

HINT:

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

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

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

(b) Disconnect the A48 No. 1 CAN junction connector.

Front view of wire harness connector

(to No. 1 CAN Junction Connector)

to Millimeter Wave Radar Sensor Assembly

to Forward Recognition Camera

to Central Gateway ECU (Network Gateway ECU)

to Swing Grille Actuator Assembly

to No. 7 CAN Junction Connector

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
A48-1 (CANH) - A48-7 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Millimeter wave radar sensor assembly
A48-2 (CANH) - A48-8 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Forward recognition camera
A48-3 (CANH) - A48-9 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Central gateway ECU (network gateway ECU)
A48-4 (CANH) - A48-10 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Swing grille actuator assembly
A48-5 (CANH) - A48-11 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 7 CAN junction connector

Result	Proceed to
OK	A
NG (Line to central gateway ECU (network gateway ECU))	B
NG (Line to No. 7 CAN junction connector)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 1 CAN JUNCTION CONNECTOR

GO TO STEP 3

GO TO STEP 5

2.	CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

(a) Disconnect the G52 central gateway ECU (network gateway ECU) connector.

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

Front view of wire harness connector

(to No. 1 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection	Condition	Specified Condition
A48-3 (CANH) - A48-9 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	1 MΩ or higher

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

3.	CHECK FOR SHORT IN CAN BUS LINES (NO. 7 CAN JUNCTION CONNECTOR)

(a) Reconnect the A48 No. 1 CAN junction connector.

(b) Disconnect the K66 No. 7 CAN junction connector.

*a	Front view of wire harness connector (to No. 7 CAN Junction Connector)	*b	to Central Gateway ECU (Network Gateway ECU)
*c	to Clearance Warning ECU Assembly (w/ Intelligent Clearance Sonar System)	*d	to Blind Spot Monitor Sensor RH
*e	to Television Camera Assembly	*f	to No. 1 CAN Junction Connector
*g	to Parking Assist ECU (w/ Panoramic View Monitor System)	*h	to Driving Support ECU Assembly

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
K66-1 (CANH) - K66-11 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Central gateway ECU (network gateway ECU)
K66-2 (CANH) - K66-12 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Clearance warning ECU assembly*1
K66-3 (CANH) - K66-13 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Blind spot monitor sensor RH
K66-4 (CANH) - K66-14 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Television camera assembly
K66-5 (CANH) - K66-15 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	No. 1 CAN junction connector
K66-8 (CANH) - K66-18 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Parking assist ECU*2
K66-9 (CANH) - K66-19 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Driving support ECU assembly

*1: w/ Intelligent Clearance Sonar System
*2: w/ Panoramic View Monitor System

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

REPLACE NO. 7 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 7 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR)

GO TO STEP 5

4.	CHECK FOR SHORT IN CAN BUS LINES (NO. 7 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

(a) Disconnect the G52 central gateway ECU (network gateway ECU) connector.

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

Front view of wire harness connector

(to No. 7 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection	Condition	Specified Condition
K66-1 (CANH) - K66-11 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	1 MΩ or higher

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 7 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

5.	CHECK FOR SHORT IN CAN BUS LINES (ECU OR SENSOR)

(a) Reconnect all wire harness connectors.

(b) 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

Standard Resistance:

Tester Connection	Condition	Specified Condition
G52-23 (CA1H) - G52-8 (CA1L)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

HINT:

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.

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

REPLACE ECU OR SENSOR

REPAIR OR REPLACE HARNESS OR CONNECTOR

Check Bus 1 Line for Short to GND

Check Bus 2 Line for Short to +B

See More:

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual > Sfi System: Low Pressure Fuel System Pressure - Too High (P008B00). Engine Coolant Temperature / Intake Air Temperature Signal Compare Failure (P011B62). Bank 1 Air-Fuel Ratio Imbalance (Port) (P11EA00-P11EF00,P1
Low Pressure Fuel System Pressure - Too High (P008B00) DESCRIPTION Refer to DTC P008A00. Click here DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory Note P008B00 Low Pressure Fuel System Pressure - Too High Actual fuel pressure (for low pressure side) value higher than target f ...