Last Modified: 08-21-2023 6.11:8.1.0 Doc ID: RM100000001R171
Model Year Start: 2021 Model: Avalon Prod Date Range: [08/2020 -           ]
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 - 2022 MY Avalon [08/2020 -        ]

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
  • Wire 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 operation being performed, 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, Gasoline Model) 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, Gasoline Model) after confirming that the communication systems are functioning properly.

    Click here 2019 - 2022 MY Avalon [04/2018 -        ]; 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 Registration.

    Click here 2021 - 2022 MY Avalon [08/2020 -        ]; 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 B279986 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.

REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID code.

Click here 2021 - 2022 MY Avalon [08/2020 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION

NEXT

2.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (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.

OK:

Tester Connection

Condition

Tool Setting

Specified Condition

A10-3 (EFII) - Body ground

Engine switch on (IG)

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 not output, or has abnormal wavelength or shape

C
B

GO TO STEP 6

C

REPLACE ECM

for 2GR-FKS: Click here 2019 - 2021 MY Avalon [04/2018 - 08/2021]; 2GR-FKS (ENGINE CONTROL): ECM: REMOVAL 2022 MY Avalon [08/2021 -        ]; 2GR-FKS (ENGINE CONTROL): ECM: REMOVAL

for A25A-FKS: Click here 2021 - 2022 MY Avalon [08/2020 -        ]; A25A-FKS (ENGINE CONTROL): ECM: REMOVAL

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

A10-4 (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) 2019 - 2021 MY Avalon Avalon HV [04/2018 - 08/2021]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL 2022 MY Avalon Avalon HV [08/2021 -        ]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL

OK

4.

REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID code.

Click here 2021 - 2022 MY Avalon [08/2020 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION

NEXT

5.

CHECK WHETHER ENGINE STARTS

(a) Using an electrical key transmitter sub-assembly which is registered to the vehicle, turn the engine switch on (IG).

(b) Check that the engine starts 5 seconds after the engine switch turned on (IG).

OK:

Engine starts normally.

OK

END (ECU COMMUNICATION ID HAS NOT BEEN REGISTERED)
NG

REPLACE ECM

for 2GR-FKS: Click here 2019 - 2021 MY Avalon [04/2018 - 08/2021]; 2GR-FKS (ENGINE CONTROL): ECM: REMOVAL 2022 MY Avalon [08/2021 -        ]; 2GR-FKS (ENGINE CONTROL): ECM: REMOVAL

for A25A-FKS: Click here 2021 - 2022 MY Avalon [08/2020 -        ]; A25A-FKS (ENGINE CONTROL): ECM: REMOVAL

6.

CHECK ECM

(a) Disconnect the A18*1 or A64*2 ECM connector.

  • *1: for 2GR-FKS
  • *2: for A25A-FKS

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

Standard Voltage:

for 2GR-FKS

Tester Connection

Condition

Specified Condition

A18-45 (IMO) - Body ground

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

Terminal IMO stuck low (2.4 V or less)

Terminal IMO stuck high (12 V) or abnormal waveform

for A25A-FKS

Tester Connection

Condition

Specified Condition

A64-25 (IMO) - Body ground

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

Terminal IMO stuck low (2.4 V or less)

Terminal IMO stuck high (12 V) or abnormal waveform

Result

Proceed to

Terminal IMO stuck low (2.4 V or less)

A

Terminal IMO stuck high (12 V) or abnormal waveform

B
B

REPLACE ECM

for 2GR-FKS: Click here 2019 - 2021 MY Avalon [04/2018 - 08/2021]; 2GR-FKS (ENGINE CONTROL): ECM: REMOVAL 2022 MY Avalon [08/2021 -        ]; 2GR-FKS (ENGINE CONTROL): ECM: REMOVAL

for A25A-FKS: Click here 2021 - 2022 MY Avalon [08/2020 -        ]; A25A-FKS (ENGINE CONTROL): ECM: REMOVAL

A

7.

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

(a) Disconnect the A10 certification ECU (smart key ECU assembly) connector.

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

Standard Resistance:

for 2GR-FKS

Tester Connection

Condition

Specified Condition

A10-3 (EFII) - A18-45 (IMO)

Always

Below 1 Ω

A10-3 (EFII) or A18-45 (IMO) - Other terminals and body ground

Always

10 kΩ or higher

for A25A-FKS

Tester Connection

Condition

Specified Condition

A10-3 (EFII) - A64-25 (IMO)

Always

Below 1 Ω

A10-3 (EFII) or A64-25 (IMO) - Other terminals and body ground

Always

10 kΩ or higher
OK

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 2019 - 2021 MY Avalon Avalon HV [04/2018 - 08/2021]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL 2022 MY Avalon Avalon HV [08/2021 -        ]; THEFT DETERRENT / KEYLESS ENTRY: CERTIFICATION ECU: REMOVAL

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR