THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): B279986; Engine Immobiliser System Signal (Some Circuit Quantity, Reported via Serial Data) Invalid; 2021 MY RAV4 [08/2020 - 12/2021]

Last Modified: 01-30-2024	6.11:8.1.0	Doc ID: RM100000001QT4W
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): B279986; Engine Immobiliser System Signal (Some Circuit Quantity, Reported via Serial Data) Invalid; 2021 MY RAV4 [08/2020 - 12/2021]

DTC

B279986

Engine Immobiliser System Signal (Some Circuit Quantity, Reported via Serial Data) Invalid

DESCRIPTION

If there is a communication malfunction between the ECM and certification ECU (smart key ECU assembly), or when the communication ID codes do not match, the ECM stores this DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B279986	Engine Immobiliser System Signal (Some Circuit Quantity, Reported via Serial Data) Invalid	Either of the following conditions is met (1 trip detection logic*): A malfunction is detected in the communication or communication lines between the ECM and certification ECU (smart key ECU assembly). The communication ID codes of the ECM and certification ECU (smart key ECU assembly) do not match.	Certification ECU (smart key ECU assembly) ECM Harness or connector	DTC output confirmation operation (Perform either of the following): Start the engine and wait for 10 seconds. If there is a malfunction, the engine will stop (communication begins within 3 seconds of the engine start, and DTCs are stored after 6 seconds). Connect the cable to the negative (-) battery terminal, start the engine and wait for 10 seconds (communication begins within 3 seconds of the engine switch being turned on (IG), and DTCs are stored after 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	-

Related Data List and Active Test

DTC No.	Data List and Active Test
B279986	-

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
Before replacing the ECM or certification ECU (smart key ECU assembly), refer to the Registration.
Click here
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

HINT:

When DTC B279986 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.	REGISTER ECU COMMUNICATION ID (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ECM)

(a) Register the communication ID codes.

HINT:

Refer to Registration.

Click here

NEXT

2.	CHECK ECM (TERMINAL EFII)

(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.

Measurement Condition:

Tester Connection

Condition

Tool Setting

Specified Condition

A15-3 (EFII) - 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)

Result	Proceed to
Normal waveform	A
Terminal EFII stuck low (2.4 V or less)	B
Waveform length or shape is abnormal, or EFII terminal stuck at Hi (12 V)	C

B

C

A

3.	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)

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

OK

4.	REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID code.

HINT:

Refer to Registration.

Click here

NEXT

5.	CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts.

Result	Proceed to
Engine was started	A
Engine was not started	B

A

END (ECU COMMUNICATION ID HAS NOT BEEN REGISTERED)

B

6.	CHECK ECM (TERMINAL IMO)

(a) Disconnect the ECM connector.

*a	Front view of wire harness connector (to ECM)

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A24-25 (IMO) - Body ground	Engine switch turned on (IG) using registered electrical key transmitter sub-assembly	Terminal IMO stuck low (2.4 V or less)
A24-25 (IMO) - Body ground		Terminal IMO stuck high (12 V)

Result	Proceed to
Terminal IMO stuck low (2.4 V or less)	A
Terminal IMO stuck high (12 V)	B

B

A

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

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A15-3 (EFII) - A24-25 (IMO)	Always	Below 1 Ω
A15-3 (EFII) or A24-25 (IMO) - Other terminals and body ground	Always	10 kΩ or higher

OK

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR