Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001H8DP
Model Year Start: 2020 Model: Corolla Prod Date Range: [01/2019 - 09/2022]
Title: THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, HV Model): B279A12; Engine Immobiliser System Circuit Short to Battery; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

DTC

B279A12

Engine Immobiliser System Circuit Short to Battery

DESCRIPTION

If the communication line (IMI - EFIO) between the hybrid vehicle control ECU and ID code box (immobiliser code ECU) is stuck high, the hybrid vehicle control ECU will store this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B279A12

Engine Immobiliser System Circuit Short to Battery

The communication line (IMI - EFIO) between the hybrid vehicle control ECU and ID code box (immobiliser code ECU) is stuck high. (1 trip detection logic*)
  • ID code box (immobiliser code ECU)
  • Hybrid vehicle control ECU
  • Wire harness or connector

DTC output confirmation operation:

  • Turn the power switch on (IG) and wait 6 seconds.
  • *: Only output while a malfunction is present.

Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected

Fail-safe Operation when Malfunction Detected

Hybrid control system cannot be started

Hybrid control system cannot be started

Related Data List and Active Test

DTC No.

Data List and Active Test

B279A12

-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When using the Techstream with the power 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 the vehicle type 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.
  • The smart key system (for Start Function) uses the LIN communication system and CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the smart key system (for Start Function) after confirming that the communication systems are functioning properly.

    Click here 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, HV Model): HOW TO PROCEED WITH TROUBLESHOOTING

  • Before replacing the hybrid vehicle control ECU or ID code box (immobiliser code ECU), refer to Registration.

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

  • After performing repairs, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

HINT:

When DTC B279A12 and the certification ECU (smart key ECU assembly) DTC are output simultaneously, first perform troubleshooting for the certification ECU (smart key ECU assembly) DTC.

PROCEDURE

1.

CHECK CONNECTION OF CONNECTOR

(a) Turn the power switch off.

(b) Check that the connectors are properly connected to the hybrid vehicle control ECU and ID code box (immobiliser code ECU).

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY
OK

2.

CHECK WHETHER HYBRID CONTROL SYSTEM STARTS

(a) Check that the hybrid control system starts.

OK:

Hybrid control system starts normally.

OK

USE SIMULATION METHOD TO CHECK

NG

3.

CHECK HYBRID VEHICLE CONTROL ECU (TERMINAL IMI)

(a) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(Hybrid Vehicle Control ECU)

*b

Waveform

*c

Approximately 160 ms.

*d

Approximately 270 ms.

OK:

Tester Connection

Condition

Tool Setting

Specified Condition

I3-10 (IMI) - Body ground

Within 3 seconds of hybrid control system start or within 3 seconds of power switch turned on (IG) after cable disconnected and reconnected to auxiliary battery

2 V/DIV., 500 ms./DIV.

Pulse generation

(See waveform)

Result

Proceed to

11 to 14 V

A

Below 1 V

B

Normal wavform
B

REPLACE HYBRID VEHICLE CONTROL ECU 2020 MY Corolla Corolla HV [01/2019 - 04/2020]; HYBRID / BATTERY CONTROL: HYBRID VEHICLE CONTROL ECU: REMOVAL 2021 - 2022 MY Corolla Corolla HV [04/2020 - 09/2022]; HYBRID / BATTERY CONTROL: HYBRID VEHICLE CONTROL ECU: REMOVAL

A

4.

CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILISER CODE ECU) - HYBRID VEHICLE CONTROL ECU)

(a) Disconnect the I3 hybrid vehicle control ECU connector.

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I20-4 (EFIO) - I3-10 (IMI)

Always

Below 1 Ω
OK

REPLACE ID CODE BOX (IMMOBILISER CODE ECU) 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

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR