Last Modified: 07-31-2024 6.11:8.1.0 Doc ID: RM100000001GVZA
Model Year Start: 2020 Model: Corolla Prod Date Range: [01/2019 - 09/2022]
Title: NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): Check Bus 5 Line for Short to GND; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

Check Bus 5 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 15 (CA5H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 16 (CA5L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom

Trouble Area

There is no resistance between terminal 15 (CA5H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 16 (CA5L) 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)
  • Air conditioning amplifier assembly
  • Certification ECU (smart key ECU assembly)
  • Main body ECU (multiplex network body ECU)
  • Combination meter assembly
  • No. 3 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 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]; NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): HOW TO PROCEED WITH TROUBLESHOOTING

  • 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 10 minutes 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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  • 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 2020 MY Corolla Corolla HV [01/2019 - 04/2020]; NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): DIAGNOSIS SYSTEM 2021 - 2022 MY Corolla Corolla HV [04/2020 - 09/2022]; NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): DIAGNOSIS SYSTEM

  • Before replacing the main body ECU (multiplex network body ECU) or certification ECU (smart key ECU assembly), refer to Service Bulletin.

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. 3 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the I94 No. 3 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. 3 CAN Junction Connector)

*b

to Combination Meter Assembly

*c

to Main Body ECU (Multiplex Network Body ECU)

*d

to Air Conditioning Amplifier Assembly

*e

to Certification ECU (Smart Key ECU Assembly)

*f

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

I94-1 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

Combination meter assembly

I94-11 (CANL) - I26-4 (CG)

I94-2 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

Main body ECU (multiplex network body ECU)

I94-12 (CANL) - I26-4 (CG)

I94-4 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

Air conditioning amplifier assembly

I94-14 (CANL) - I26-4 (CG)

I94-5 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

Certification ECU (smart key ECU assembly)

I94-15 (CANL) - I26-4 (CG)

I94-6 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

Central gateway ECU (network gateway ECU)

I94-16 (CANL) - I26-4 (CG)

Result

Proceed to

OK

A

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

B

NG (Line to ECU or sensor)

C
A

REPLACE NO. 3 CAN JUNCTION CONNECTOR
C

GO TO STEP 3

B

2.

CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

(a) Disconnect the I53 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. 3 CAN Junction Connector)

*b

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection

Condition

Specified Condition

I94-6 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

I94-16 (CANL) - I26-4 (CG)
OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

3.

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.

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(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

I53-15 (CA5H) - I26-4 (CG)

Cable disconnected from negative (-) auxiliary battery terminal

200 Ω or higher

I53-16 (CA5L) - I26-4 (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