THEFT DETERRENT / KEYLESS ENTRY: IMMOBILISER SYSTEM (w/o Smart Key System): B279A12,B279A; Engine Immobiliser System Circuit Short to Battery; 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM100000001GV8B
Model Year Start: 2020	Model: GR Corolla	Prod Date Range: [01/2019 - 09/2022]
Title: THEFT DETERRENT / KEYLESS ENTRY: IMMOBILISER SYSTEM (w/o Smart Key System): B279A12,B279A; Engine Immobiliser System Circuit Short to Battery; 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 09/2022]

DTC

B279A12

Engine Immobiliser System Circuit Short to Battery

DTC

B279A

Theft Deterrent System Communication Line High Fixation

DESCRIPTION

If the communication line (EFIO-IMI) to the transponder key ECU assembly is stuck high (e.g. shorted to +B), the ECM stores this DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B279A	Theft Deterrent System Communication Line High Fixation	Communication line (EFIO-IMI) between the ECM and transponder key ECU assembly is stuck high.	Wire harness or connector ECM Transponder key ECU assembly	DTC Output Confirmation Operation: Turn the ignition switch to ON and wait 6 seconds.
B279A12	Engine Immobiliser System Circuit Short to Battery	Communication line (EFIO-IMI) between the ECM and transponder key ECU assembly is stuck high.	Wire harness or connector ECM Transponder key ECU assembly	DTC Output Confirmation Operation: Turn the ignition switch to ON and wait 6 seconds.

Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected	Fail-safe Operation when Malfunction Detected
Engine cannot be started (initial ignition occurs and engine cranks, then ignition stops)	Engine cannot be started

Related Data List and Active Test

DTC No.	Data List and Active Test
B279A*1	-
B279A12*2	-

*1: for 2ZR-FAE
*2: for M20A-FKS

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

If the transponder key ECU assembly or ECM is replaced, refer to Registration.
Click here
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

PROCEDURE

1.	CHECK CONNECTION OF CONNECTOR

(a) Check that the connectors are properly connected to the ECM and transponder key ECU assembly.

OK:

Connectors are properly connected.

CONNECT CONNECTORS PROPERLY

CHECK ECM

(a) Disconnect the I67 transponder key ECU assembly connector.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
I67-11 (EFIO) - Body ground	Always	11 to 14 V

GO TO STEP 4

3.	CHECK TRANSPONDER KEY ECU ASSEMBLY (TERMINAL EFIO)

(a) Connect the I67 transponder key ECU assembly connector.

(b) Using an oscilloscope, check the waveform.

Component with harness connected

(Transponder Key ECU Assembly)

Waveform

Approximately 160 ms.

Approximately 270 ms.

OK:

Tester Connection

Condition

Tool Setting

Specified Condition

I67-11 (EFIO) - Body ground

Within 3 seconds of starter operation and initial combustion, or within 3 seconds of ignition switch first being turned to ON after cable disconnected and reconnected to negative (-) battery terminal

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

Pulse generation

(See waveform)

REPLACE ECM

for M20A-FKS: Click here

for 2ZR-FAE: Click here

REPLACE TRANSPONDER KEY ECU ASSEMBLY

4.	CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU ASSEMBLY - ECM)

(a) Disconnect the A46*1 or A47*2 ECM connector.

*1: for 2ZR-FAE
*2: for M20A-FKS

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

Standard Resistance:

for 2ZR-FAE

Tester Connection	Condition	Specified Condition
I67-11 (EFIO) - A46-28 (IMI)	Always	Below 1 Ω
I67-11 (EFIO) or A46-28 (IMI) - Other terminals and body ground	Always	10 kΩ or higher

for M20A-FKS

Tester Connection	Condition	Specified Condition
I67-11 (EFIO) - A47-26 (IMI)	Always	Below 1 Ω
I67-11 (EFIO) or A47-26 (IMI) - Other terminals and body ground	Always	10 kΩ or higher