Toyota Tacoma manuals

Toyota Tacoma (2015-2018) Service Manual: Engine Immobiliser System Signal (Some Circuit Quantity, Reported via Serial Data) Invalid (B279986)

Toyota Tacoma (2015-2018) Service Manual / Engine Immobiliser / Engine Immobiliser System(w/ Smart Key System) / Engine Immobiliser System Signal (Some Circuit Quantity, Reported via Serial Data) Invalid (B279986)

DESCRIPTION

When there are communication malfunctions 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 Code

DTC Detection Condition

Trouble Area

DTC Output Confirmation Operation

B279986

Either condition is met (1 trip detection logic*1):

  • A malfunction in the communication or communication lines between the ECM and certification ECU (smart key ECU assembly)
  • A matching communication code cannot be verified during communication between the ECM and certification ECU (smart key ECU assembly).
  • Certification ECU (smart key ECU assembly)
  • ECM
  • Wire harness or connector

Either condition is met:

  • Within 10 seconds of an engine start operation being performed (with the shift lever in P and the brake pedal depressed, the engine switch is pressed while carrying the key). If there is a malfunction, the engine stops (communication begins within 3 seconds of the engine start operation being performed, and DTCs are stored after 6 seconds).
  • 10 seconds after the engine switch is turned on (IG) after reconnecting the cable to the negative (-) battery terminal (communication begins within 3 seconds of the engine switch being turned on (IG), and DTCs are stored after 6 seconds).
  • *1: 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 Code

Data List and Active Test

B279986

-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION / NOTICE / HINT

NOTICE:

  • When replacing the certification ECU (smart key ECU assembly), refer to Registration (See page After performing repairs, perform the operation that fulfills the DTC .
  • After performing repairs, perform the operation that fulfills the DTC output confirmation operation, and then confirm that no DTCs are output again.

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 (See page ).

NEXT

2.

CLEAR DTC

(a) Clear the DTCs (See page ).

NEXT

3.

CHECK FOR DTC

(a) Start the engine.

(b) Perform "DTC Output Confirmation Operation" procedure.

(c) Check for DTCs (See page OK: ).

OK:

DTC B279986 is not output.

Result

Result

Proceed to

OK

A

NG (DTC B279986 is output)

B

NG (Other DTCs are output)

C
A

END (COMMUNICATION ID REGISTRATION WAS DEFECTIVE)
C

GO TO DIAGNOSTIC TROUBLE CODE CHART

B

4.

INSPECT ECM (TERMINAL IMO)

(a) Using an oscilloscope, check the waveform.

Text in Illustration

*a

Component with harness connected

(ECM)

*b

Waveform

Measurement Condition:

Tester Connection

Condition

Tool Setting

Specified Condition

E14-9 (IMO) - Body ground

Within 3 seconds of engine start or within 3 seconds of engine switch turned on (IG) after battery cable disconnected and reconnected

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

Pulse generation

(See waveform)

OK:

The waveform is similar to that shown in the illustration.

Result

Result

Proceed to

Normal waveform

A

Terminal IMO stuck low (2.4 V or less)

B

Terminal IMO stuck high (12 V), or has abnormal wavelength or shape

C
B

GO TO STEP 8

C

REPLACE ECM

A

5.

INSPECT CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (TERMINAL IMI)

(a) Using an oscilloscope, check the waveform.

Text in Illustration

*a

Component with harness connected

(ECM)

*b

Waveform

Measurement Condition:

Tester Connection

Condition

Tool Setting

Specified Condition

E14-8 (IMI) - Body ground

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

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

Pulse generation

(See waveform)

OK:

The waveform is similar to that shown in the illustration.

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

OK

6.

REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID (See page ).

NEXT

7.

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 was turned on (IG).

OK:

Engine starts normally.

OK

END (COMMUNICATION ID REGISTRATION WAS DEFECTIVE)
NG

REPLACE ECM

8.

INSPECT ECM (IMO TERMINAL VOLTAGE)

(a) Disconnect the ECM connector.

(b) Turn the engine switch on (IG).

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

E14-9 (IMO) - Body ground

Engine switch 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
Text in Illustration

*a

Front view of wire harness connector

(to ECM)
Result

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

A

9.

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

(a) Disconnect the C27 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the E14 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

C27-7 (EFII) - E14-9 (IMO)

Always

Below 1 Ω

C27-7 (EFII) or E14-9 (IMO) - Body ground

Always

10 kΩ or higher

C27-6 (EFIO) - E14-8 (IMI)

Always

Below 1 Ω

C27-6 (EFIO) or E14-8 (IMI) - Body ground

Always

10 kΩ or higher
OK

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
Antenna Coil Open / Short (B2784)
DESCRIPTION When an open or short circuit is detected in the transponder key amplifier coil built into the engine switch, the certification ECU (smart key ECU assembly) stores this DTC. This DTC ...

Malfunction of ID-BOX Recognition (B278D)
DESCRIPTION When the certification ECU (smart key ECU assembly) detects an input signal indicating that the vehicle is equipped with an ID code box even though the ID code box is not registered, ...

Other materials:

Components
COMPONENTS ILLUSTRATION *A for Double Cab *B w/o Woofer *C w/ Woofer - - *1 LUGGAGE COMPARTMENT SIDE TRAY RH - - ILLUSTRATION *A ...

Disassembly
DISASSEMBLY PROCEDURE 1. REMOVE NO. 1 HEATER TO REGISTER DUCT (a) Remove the 2 screws <F> and screw <D>. (b) Disengage the 2 guides to remove the No. 1 heater to register duct. 2. REMOVE NO. 3 HEATER TO REGISTER DUCT ...

Adjustment
ADJUSTMENT CAUTION / NOTICE / HINT HINT: Centering bolts are used to mount the hood hinge and hood lock assembly. The hood and hood lock assembly cannot be adjusted with the centering bolts installed. Substitute the centering bolts with standard bolts when making adjustments ...

© 2011-2025 Copyright www.ttguide.net