Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Check Bus 4 Line for Short to +B

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Power Source, Network / Networking / Can Communication System(for Gasoline Model) / Check Bus 4 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when there is no resistance between terminal 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 7 (CA2L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Symptom

Trouble Area

There is no resistance between terminal 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 7 (CA2L) 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)
  • Occupant detection ECU
  • Tire pressure warning ECU and receiver
  • Rack and pinion power steering gear assembly
  • Brake actuator assembly
  • Steering sensor
  • Airbag ECU assembly
  • Absorber control ECU

    (w/ AVS System)

  • No. 2 CAN junction connector
  • No. 4 CAN junction connector
  • No. 1 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 engine 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 engine 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 engine 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 TO +B IN CAN BUS LINE (NO. 1 JUNCTION CONNECTOR)

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

(b) Disconnect the K67 No. 1 junction connector.

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

*1

DLC3

-

-

*a

Front view of wire harness connector

(to No. 1 Junction Connector)

*b

to Absorber Control ECU

(w/ AVS System)

*c

to Tire Pressure Warning ECU and Receiver

*d

to Occupant Detection ECU

*e

to Central Gateway ECU (Network Gateway ECU)

*f

to No. 2 CAN Junction Connector

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

K67-7 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Absorber control ECU*

K67-18 (CANL) - G45-16 (BAT)

K67-8 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Tire pressure warning ECU and receiver

K67-19 (CANL) - G45-16 (BAT)

K67-9 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Occupant detection ECU

K67-20 (CANL) - G45-16 (BAT)

K67-10 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Central gateway ECU (network gateway ECU)

K67-21 (CANL) - G45-16 (BAT)

K67-11 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

No. 2 CAN junction connector

K67-22 (CANL) - G45-16 (BAT)
  • *: w/ AVS System

Result

Proceed to

OK

A

NG (Line to central gateway ECU (network gateway ECU))

B

NG (Line to No. 2 CAN junction connector)

C

NG (Line to ECU or sensor)

D
A

REPLACE NO. 1 JUNCTION CONNECTOR
C

GO TO STEP 3

D

GO TO STEP 7

B

2.

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

*1

DLC3

-

-

*a

Front view of wire harness connector

(to No. 1 Junction Connector)

*b

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection

Condition

Specified Condition

K67-10 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

K67-21 (CANL) - G45-16 (BAT)
OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

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

3.

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

(a) Disconnect the A49 No. 2 CAN junction connector.

(b) 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 Brake Actuator Assembly

*c

to No. 1 Junction Connector

*d

to Rack and Pinion Power Steering Gear Assembly

*e

to No. 4 CAN Junction Connector

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

A49-1 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Brake actuator assembly

A49-12 (CANL) - G45-16 (BAT)

A49-2 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

No. 1 junction connector

A49-13 (CANL) - G45-16 (BAT)

A49-4 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Rack and pinion power steering gear assembly

A49-15 (CANL) - G45-16 (BAT)

A49-5 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

No. 4 CAN junction connector

A49-16 (CANL) - G45-16 (BAT)

Result

Proceed to

OK

A

NG (Line to No. 1 junction connector)

B

NG (Line to No. 4 CAN junction connector)

C

NG (Line to ECU or sensor)

D
A

REPLACE NO. 2 CAN JUNCTION CONNECTOR
B

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

GO TO STEP 7

C

4.

CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR)

(a) Disconnect the G96 No. 4 CAN junction connector.

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

*1

DLC3

-

-

*a

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

*b

to Airbag ECU Assembly

Standard Resistance:

Tester Connection

Condition

Specified Condition

G96-6 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

G96-17 (CANL) - G45-16 (BAT)
NG

GO TO STEP 6

OK

5.

CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR)

(a) Disconnect the G95 No. 4 CAN junction connector.

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

*1

DLC3

-

-

*a

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

*b

to No. 2 CAN Junction Connector

*c

to Steering Sensor

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

G95-6 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

No. 2 CAN junction connector

G95-17 (CANL) - G45-16 (BAT)

G95-7 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Steering sensor

G95-18 (CANL) - G45-16 (BAT)

Result

Proceed to

OK

A

NG (Line to No. 2 CAN junction connector)

B

NG (Line to ECU or sensor)

C
A

REPLACE NO. 4 CAN JUNCTION CONNECTOR
B

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)
C

GO TO STEP 7

6.

CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR - AIRBAG ECU ASSEMBLY)

(a) Disconnect the G50 airbag ECU assembly connector.

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

*1

DLC3

-

-

*a

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

*b

to Airbag ECU Assembly

Standard Resistance:

Tester Connection

Condition

Specified Condition

G96-6 (CANH) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

G96-17 (CANL) - G45-16 (BAT)
OK

REPLACE AIRBAG ECU ASSEMBLY

NG

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - AIRBAG ECU ASSEMBLY)

7.

CHECK FOR SHORT TO +B IN CAN BUS LINE (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 bus line shorted to +B is connected.

Click here

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

*1

DLC3

-

-

*a

Component with harness connected

(Central Gateway ECU (Network Gateway ECU))

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

G52-22 (CA2H) - G45-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

G52-7 (CA2L) - G45-16 (BAT)

HINT:

  • 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.
OK

REPLACE ECU OR SENSOR
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
    Check Bus 3 Lines for Short Circuit

    Check Bus 4 Line for Short to GND

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