Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Check Bus 2 Line for Short to GND

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Power Source, Network / Networking / Can Communication System(for Hv Model) / 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

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.
  • Short to ground in CAN main bus line
  • Short to ground in CAN branch line
  • Central gateway ECU (network gateway ECU)
  • ECM
  • Hybrid vehicle control ECU
  • Brake booster with master cylinder assembly
  • Inverter with converter assembly
  • No. 2 CAN junction connector
  • No. 4 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 TO GND IN CAN BUS LINE (NO. 2 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the A49 No. 2 CAN 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. 2 CAN Junction Connector)

*b

to Inverter with Converter Assembly

*c

to Brake Booster with Master Cylinder Assembly

*d

to No. 4 CAN Junction Connector

*e

to ECM

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

A49-8 (CANH) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

Inverter with converter assembly

A49-19 (CANL) - G45-4 (CG)

A49-9 (CANH) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

Brake booster with master cylinder assembly

A49-20 (CANL) - G45-4 (CG)

A49-10 (CANH) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

No. 4 CAN junction connector

A49-21 (CANL) - G45-4 (CG)

A49-11 (CANH) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

ECM

A49-22 (CANL) - G45-4 (CG)

Result

Proceed to

OK

A

NG (Line to No. 4 CAN junction connector)

B

NG (Line to ECU or sensor)

C
A

REPLACE NO. 2 CAN JUNCTION CONNECTOR
C

GO TO STEP 5

B

2.

CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 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 Hybrid Vehicle Control ECU

*c

to No. 2 CAN Junction Connector

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

G96-9 (CANH) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

Hybrid vehicle control ECU

G96-20 (CANL) - G45-4 (CG)

G96-11 (CANH) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

No. 2 CAN junction connector

G96-22 (CANL) - G45-4 (CG)

Result

Proceed to

OK

A

NG (Line to No. 2 CAN junction connector)

B

NG (Line to ECU or sensor)

C
B

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

GO TO STEP 5

A

3.

CHECK FOR SHORT TO GND 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 Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection

Condition

Specified Condition

G95-1 (CANH) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

G95-12 (CANL) - G45-4 (CG)
OK

REPLACE NO. 4 CAN JUNCTION CONNECTOR
NG

4.

CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 4 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.

*1

DLC3

-

-

*a

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

*b

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection

Condition

Specified Condition

G95-1 (CANH) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

G95-12 (CANL) - G45-4 (CG)
OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

5.

CHECK FOR SHORT TO GND 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 GND 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

G52-18 (CA4H) - G45-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

G52-17 (CA4L) - G45-4 (CG)

HINT:

  • 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.
OK

REPLACE ECU OR SENSOR
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
    Check Bus 2 Line for Short to +B

    Check Bus 2 Lines for Short Circuit

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