Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001CY53
Model Year Start: 2019 Model: GR Corolla Prod Date Range: [06/2018 - 09/2022]
Title: NETWORKING: LIN COMMUNICATION SYSTEM (for Gasoline Model): B2785; Communication Malfunction between ECUs Connected by LIN; 2019 - 2022 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 09/2022]

DTC

B2785

Communication Malfunction between ECUs Connected by LIN

DESCRIPTION

If the certification ECU (smart key ECU assembly) detects a communication error with an ECU connected to the certification bus lines for 7 seconds or more, DTC B2785 will be stored.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B2785

Communication Malfunction between ECUs Connected by LIN
  • Errors in LIN communication between ECUs or an open or short in communication lines.
  • The certification ECU (smart key ECU assembly) detects a communication error with an ECU connected to the certification bus lines for 7 seconds or more.
  • Certification ECU (smart key ECU assembly)
  • Steering lock ECU (steering lock actuator or upper bracket assembly)
  • ID code box (immobiliser code ECU)
  • Wire harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Before performing the inspection, check that DTC B2786 or B278C is not output.

    Click here 2019 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 01/2019]; NETWORKING: LIN COMMUNICATION SYSTEM (for Gasoline Model): DTC CHECK / CLEAR 2020 - 2022 MY Corolla Corolla Hatchback GR Corolla [01/2019 - 09/2022]; NETWORKING: LIN COMMUNICATION SYSTEM (for Gasoline Model): DTC CHECK / CLEAR

  • When using the Techstream with the engine switch off, connect the Techstream to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the Techstream and the vehicle begins. Then select Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Smart Key. While using the Techstream, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the Techstream and the vehicle.
  • Before replacing the certification ECU (smart key ECU assembly), ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator or upper bracket assembly), refer to Registration.

    Click here 2019 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 01/2019]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION 2020 MY Corolla Corolla Hatchback GR Corolla [01/2019 - 09/2019]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION 2020 MY Corolla Corolla Hatchback GR Corolla [09/2019 - 04/2020]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION 2021 - 2022 MY Corolla Corolla Hatchback GR Corolla [04/2020 - 09/2022]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - EACH ECU)

(a) Disconnect the I1 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the I59 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

(c) Disconnect the I20 ID code box (immobiliser code ECU) connector.

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

NOTICE:

Make sure that each ECU is in sleep mode before performing the inspection. To enter sleep mode, turn the engine switch from on (IG) to off and wait for 180 seconds or more without operating any switches.

Standard Resistance:

Tester Connection

Condition

Specified Condition

I1-14 (LIN) - I59-5 (LIN)

Engine switch off

Below 1 Ω

I1-14 (LIN) - I20-2 (LIN1)

Engine switch off

Below 1 Ω

I1-14 (LIN), I59-5 (LIN) or I20-2 (LIN1) - Body ground

Engine switch off

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

2.

CHECK FOR DTC (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Connect the I1 certification ECU (smart key ECU assembly) connector.

(b) Connect the I20 ID code box (immobiliser code ECU) connector.

(c) Clear the DTCs.

Body Electrical > Smart Key > Clear DTCs

(d) Recheck for DTCs.

Body Electrical > Smart Key > Trouble Codes

Result

Proceed to

DTC B2785 is output

A

DTC B2785 is not output

B
B

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY) 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; STEERING COLUMN: STEERING COLUMN ASSEMBLY: DISASSEMBLY 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 09/2022]; STEERING COLUMN: STEERING COLUMN ASSEMBLY: DISASSEMBLY

A

3.

CHECK FOR DTC (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Connect the I59 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

(b) Disconnect the I20 ID code box (immobiliser code ECU) connector.

(c) Clear the DTCs.

Body Electrical > Smart Key > Clear DTCs

(d) Recheck for DTCs.

Body Electrical > Smart Key > Trouble Codes

Result

Proceed to

DTC B2785 is output

A

DTC B2785 is not output

B
A

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL

B

REPLACE ID CODE BOX (IMMOBILISER CODE ECU) 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; THEFT DETERRENT / KEYLESS ENTRY: ID CODE BOX: REMOVAL 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; THEFT DETERRENT / KEYLESS ENTRY: ID CODE BOX: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; THEFT DETERRENT / KEYLESS ENTRY: ID CODE BOX: REMOVAL