Toyota Tundra Service Manual: Antenna Coil Open / Short (B2784)

Toyota Tundra Service Manual / Vehicle Interior / Engine Immobiliser / Engine Immobiliser System (w/o Smart Key System) / Antenna Coil Open / Short (B2784)

DESCRIPTION

When an open or short circuit is detected in the transponder key amplifier built into the transponder key ECU assembly, the transponder key ECU assembly stores this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2784

Antenna Coil Open / Short

The antenna coil in the transponder key coil is open/shorted (1 trip detection logic*).
  • Harness or connector
  • Transponder key coil
  • Transponder key ECU assembly
  • Insert the key into the ignition key cylinder.
  • *: 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

B2784

Antenna Coil Status

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • If the transponder key ECU assembly is replaced, refer to Registration.

    Click here

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

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

NEXT

2.

CHECK FOR DTC

(a) Check for DTCs.

Click here

HINT:

Before checking for DTCs, perform the "DTC Output Confirmation Operation" procedure.

OK:

DTC B2784 is not output.

Result

Proceed to

B2784 is not output

A

B2784 is output

B
A

USE SIMULATION METHOD TO CHECK

B

3.

CHECK CONNECTION OF CONNECTOR

(a) Check that the connectors are properly connected to the transponder key coil.

NEXT

4.

CLEAR DTC

(a) Clear the DTCs.

Click here

NEXT

5.

CHECK FOR DTC

(a) Check for DTCs.

Click here

HINT:

Before checking for DTCs, perform "DTC Output Confirmation Operation" procedure.

OK:

DTC B2784 is not output.

Result

Proceed to

B2784 is not output

A

B2784 is output

B
A

END (CONNECTOR WAS NOT CONNECTED PROPERLY)
B

6.

CHECK TRANSPONDER KEY COIL (OUTPUT)

(a) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(Transponder Key Coil)

*b

Waveform 1

*c

Waveform 2

-

-
Waveform 1

Item

Content

Tester Connection

J168-1 (ANT1) - Body ground

Tool Setting

20 V/DIV., 2 s./DIV.

Condition

Within 3 seconds of inserting key into ignition key cylinder
Waveform 2

Item

Content

Tester Connection

J168-5 (ANT2) - Body ground

Tool Setting

20 V/DIV., 2 s./DIV.

Condition

Within 3 seconds of inserting key into ignition key cylinder

OK:

Waveform is similar to that shown in the illustration.

OK

REPLACE TRANSPONDER KEY COIL

NG

7.

CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU ASSEMBLY - TRANSPONDER KEY COIL AND BODY GROUND)

(a) Disconnect the J26 transponder key ECU assembly connector.

(b) Disconnect the J168 transponder key coil connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J26-4 (ANT1) - J168-1 (ANT1)

Always

Below 1 Ω

J26-15 (ANT2) - J168-5 (ANT2)

Always

Below 1 Ω

J26-4 (ANT1) - Body ground

Always

10 kΩ or higher

J168-1 (ANT1) - Body ground

Always

10 kΩ or higher

J26-15 (ANT2) - Body ground

Always

10 kΩ or higher

J168-5 (ANT2) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

8.

REPLACE TRANSPONDER KEY ECU ASSEMBLY

(a) Replace the transponder key ECU assembly with a new one.

Click here

NOTICE:

Key ID code registration is necessary when replacing the transponder key ECU assembly.

Click here

NEXT

9.

CLEAR DTC

(a) Clear the DTCs.

Click here

NEXT

10.

CHECK FOR DTC

(a) Check for DTCs.

Click here

HINT:

Before checking for DTCs, perform the "DTC Output Confirmation Operation" procedure.

OK:

DTC B2784 is not output.

Result

Proceed to

B2784 is not output

A

B2784 is output

B
A

END (TRANSPONDER KEY ECU ASSEMBLY WAS DEFECTIVE)
B

REPLACE TRANSPONDER KEY COIL

    Push Switch / Key Unlock Warning Switch Malfunction (B2780)

    Transponder Chip Malfunction (B2793,B2794,B2797,B2798)

    See More:

    Toyota Tundra Service Manual > Lane Departure Alert System: Lost Communication with Yaw Rate Sensor Module (U0123,U0126,U0129,U0142,U0155)
    DESCRIPTION These DTCs are output when a communication malfunction occurs between the sensors and ECUs. DTC No. Detection Item DTC Detection Condition Trouble Area U0123 Lost Communication with Yaw Rate Sensor Module 3 seconds after the ignition switch is turned to ON, the vehicle is being driven at ...

    Toyota Tundra Owners Manual

    Toyota Tundra Service Manual

    © 2025 Copyright www.ttundra.com
    0.0109