Toyota Tacoma 2015-2018 Service Manual: Antenna Coil Open / Short (B2784)

Toyota Tacoma 2015-2018 Service Manual / Engine Immobiliser / Engine Immobiliser System(w/ Smart Key System) / 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 is also stored as a past DTC.

DTC Code	DTC Detection Condition	Trouble Area	DTC Output Confirmation Operation
B2784	The transponder key amplifier coil built into the engine switch is open (see below) or shorted (determined by communication with certification ECU (smart key ECU assembly)) (1 trip detection logic*). Terminal AGND, VC5, TXCT or CODE is open (includes disconnection of the engine switch). The transponder key amplifier coil built into the engine switch is open.	Engine switch Wire harness or connector Certification ECU (smart key ECU assembly)	With the shift lever in P, the key held near the engine switch and an engine start operation is performed by pressing and holding the engine switch when the key battery is depleted.

*: 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 when key battery is depleted by holding key near engine switch and pressing and holding engine switch with shift lever in P	-

Related Data List and Active Test

DTC Code	Data List and Active Test
B2784	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE

CLEAR DTC

(a) Clear the DTCs (See page ).

2.	CHECK DTC OUTPUT

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

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

OK:

DTC B2784 is not output.

USE SIMULATION METHOD TO CHECK

3.	CHECK ENGINE SWITCH (OUTPUT)

(a) Using an oscilloscope, check the waveform.

Text in Illustration

Component with harness connected

(Engine Switch)

Waveform

Waveform (detail)

Measurement Condition:

Tester Connection	Condition	Tool Setting	Specified Condition
E28-8 (CODE) - E28-6 (AGND)	Engine switch off, engine switch pressed with key held near engine switch*	1 V/DIV., 20 ms./DIV.	Pulse generation (See waveform)
2 V/DIV., 100 μs./DIV.	Pulse generation (See waveform (detail))

Tester Connection

Condition

Tool Setting

Specified Condition

E28-8 (CODE) - E28-6 (AGND)

Engine switch off, engine switch pressed with key held near engine switch*

1 V/DIV., 20 ms./DIV.

Pulse generation

(See waveform)

2 V/DIV., 100 μs./DIV.

Pulse generation

(See waveform (detail))

*: Remove the key battery before performing this inspection.

OK:

The waveform is similar to that shown in the illustration

REPLACE ENGINE SWITCH

4.	REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Replace the certification ECU (smart key ECU assembly) with a new one (See page ).

5.	REGISTER RECOGNITION CODE

(a) Register the key (See page ).

6.	REGISTER ECU COMMUNICATION ID

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

CLEAR DTC

(a) Clear the DTCs (See page ).

8.	CHECK FOR DTC

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

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

OK:

DTC B2784 is not output.

END (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) WAS DEFECTIVE)

REPLACE ENGINE SWITCH

Engine Immobiliser System Incorrect Assembly (B279C95)

DESCRIPTION This code is stored when an ECM that is incompatible with the engine immobiliser system is installed to the vehicle. DTC Code DTC Detection Condition T ...

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. ...

Other materials:

Front Occupant Classification Sensor LH Circuit Malfunction (B1780)
DESCRIPTION The occupant classification sensor front LH circuit consists of the occupant detection ECU and the occupant classification sensor front LH. DTC B1780 is set when a malfunction is detected in the occupant classification sensor front LH circuit. DTC No. DTC Det ...

Disassembly
DISASSEMBLY CAUTION / NOTICE / HINT HINT: Use the same procedure for both the LH and RH sides. The procedure described below is for the LH side. PROCEDURE 1. REMOVE NO. 1 HEADLIGHT BULB (a) Turn the No. 1 headlight bulb in the direction indicated by the arrow i ...

Ignition Hold Monitor Malfunction (B2271)
DESCRIPTION This DTC is stored when a malfunction in the IG circuit or IG hold circuit in the certification ECU (smart key ECU assembly) is detected. HINT: When the cable is disconnected and reconnected to the negative (-) battery terminal, the power source mode returns to the state it was in ...