Last Modified: 07-31-2024 6.11:8.1.0 Doc ID: RM100000001CY6J
Model Year Start: 2019 Model: GR Corolla Prod Date Range: [06/2018 - 01/2019]
Title: THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): B279A12; Engine Immobiliser System Circuit Short to Battery; 2019 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 01/2019]

DTC

B279A12

Engine Immobiliser System Circuit Short to Battery

DESCRIPTION

If the communication line (IMI - EFIO) between the ECM and ID code box (immobiliser code ECU) is stuck high, the ECM 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 ECM and ID code box (immobiliser code ECU) is stuck high. (1 trip detection logic*)
  • ID code box (immobiliser code ECU)
  • ECM
  • Wire harness or connector

DTC output confirmation operation:

  • Turn the engine 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

Engine cannot be started

Engine 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 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 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 2019 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 01/2019]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): HOW TO PROCEED WITH TROUBLESHOOTING

  • Before replacing the ECM, ID code box (immobiliser code ECU), 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

  • 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 engine switch off.

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

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY
OK

2.

CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts.

OK:

Engine starts normally.

OK

USE SIMULATION METHOD TO CHECK

NG

3.

CHECK ECM (TERMINAL EFIO)

(a) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

I20-4 (EFIO) - Body ground

Engine switch on (IG)

11 to 14 V

*a

Component with harness connected

(ID Code Box (Immobiliser Code ECU))
NG

GO TO STEP 5

OK

4.

CHECK ID CODE BOX (IMMOBILISER CODE ECU) (TERMINAL EFIO)

(a) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(ID Code Box (Immobiliser Code ECU))

*b

Waveform

*c

Approximately 160 ms.

*d

Approximately 270 ms.

OK:

Tester Connection

Condition

Tool Setting

Specified Condition

I20-4 (EFIO) - Body ground

Within 3 seconds of engine start or within 3 seconds of engine switch turned on (IG) after cable disconnected and reconnected to battery

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

Pulse generation

(See waveform)
OK

REPLACE ECM

NG

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

5.

CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILISER CODE ECU) - ECM)

(a) Disconnect the A47 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I20-4 (EFIO) - A47-26 (IMI)

Always

Below 1 Ω
OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR