NETWORKING: CAN COMMUNICATION SYSTEM (for Gasoline Model except TMC Made): Check Bus 2 Line for Short to GND; 2023 MY Corolla Corolla Hatchback GR Corolla [09/2022

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
TCM
(for CVT (K120))
No. 4 CAN junction connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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.
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Before measuring the resistance of the CAN bus, turn the ignition 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 10 minutes or more before measuring the resistance.
When disconnecting and reconnecting the battery.
HINT:

When disconnecting and reconnecting the battery, there is an automatic learning function that completes learning when the respective system is used.

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Some parts must be initialized and set when replacing or removing and installing parts.
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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 ignition switch to ON 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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PROCEDURE

Tester Connection

Condition

Specified Condition

Connected to

I95-9 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

Central gateway ECU (network gateway ECU)

I95-20 (CANL) - I26-4 (CG)

I95-10 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

ECM

I95-21 (CANL) - I26-4 (CG)

I95-11 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

TCM*

I95-22 (CANL) - I26-4 (CG)

Result

Proceed to

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

NG (Line to ECU or sensor)

Tester Connection

Condition

Specified Condition

I95-9 (CANH) - I26-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

I95-20 (CANL) - I26-4 (CG)

(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.

Tester Connection

Condition

Specified Condition

I53-18 (CA4H) - I26-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

I53-17 (CA4L) - 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.