Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: Engine Immobiliser System Circuit Short to Battery (B279A12)

Toyota Corolla Cross (2022-2024) Service Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Immobiliser System (w/o Smart Key System) / Engine Immobiliser System Circuit Short to Battery (B279A12)

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

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

B279A12

-

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.

NG

CONNECT CONNECTORS PROPERLY
OK

2.

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
NG

GO TO STEP 4

OK

3.

CHECK TRANSPONDER KEY ECU ASSEMBLY (TERMINAL EFIO)

(a) Connect the transponder key ECU assembly connector.

(b) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(Transponder Key ECU Assembly)

*b

Waveform

*c

Approximately 160 ms.

*d

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 (-) auxiliary battery terminal

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

Pulse generation

(See waveform)
OK

REPLACE ECM

NG

REPLACE TRANSPONDER KEY ECU ASSEMBLY

4.

CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU ASSEMBLY - 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

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
OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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