Last Modified: 01-30-2024 6.11:8.1.0 Doc ID: RM100000001QT4X
Model Year Start: 2021 Model: RAV4 Prod Date Range: [08/2020 - 12/2021]
Title: THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): B279A12; Engine Immobiliser System Circuit Short to Battery; 2021 MY RAV4 [08/2020 - 12/2021]

DTC

B279A12

Engine Immobiliser System Circuit Short to Battery

DESCRIPTION

  • If the communication line (IMI - EFIO) between the ECM and certification ECU (smart key ECU assembly) 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 certification ECU (smart key ECU assembly) is stuck high (1 trip detection logic*).
  • Harness or connector
  • Certification ECU (smart key ECU assembly)
  • ECM

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 2021 MY RAV4 [08/2020 - 12/2021]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): HOW TO PROCEED WITH TROUBLESHOOTING

  • Before replacing the ECM or certification ECU (smart key ECU assembly), refer to the Registration.

    Click here 2021 MY RAV4 [08/2020 - 12/2021]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION

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

HINT:

When DTC B279A12 and a 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 certification ECU (smart key ECU assembly).

OK:

Connectors are properly connected.

Result

Proceed to

The connectors are properly connected

A

The connectors are not properly connected

B
B

CONNECT CONNECTORS PROPERLY
A

2.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (TERMINAL EFIO)

(a) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(Certification ECU (Smart Key ECU Assembly))

*b

Waveform

*c

Approximately 160 ms.

*d

Approximately 270 ms.

OK:

Tester Connection

Condition

Tool Setting

Specified Condition

A15-4 (EFIO) - Body ground

Engine switch turned on (IG) using registered electrical key transmitter sub-assembly

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

Pulse generation

(See waveform)

Result

Proceed to

11 to 14 V

A

Below 1 V

B

Normal waveform

C
A

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

C

REPLACE ECM

B

3.

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

(a) Disconnect the A24 ECM connector.

(b) Disconnect the A15 certification ECU (smart key ECU assembly) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A15-4 (EFIO) - A24-26 (IMI)

Always

Below 1 Ω
OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR