Toyota CH-R Service Manual: Antenna Coil Open / Short (B2784)

Toyota CH-R Service Manual / Theft Deterrent / Keyless Entry / 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 history DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2784

Antenna Coil Open / Short

When either of the following conditions is met (1-trip detection logic*1):

  • The transponder key amplifier coil built into the engine switch is open (determined by communication with certification ECU (smart key ECU assembly)).
  • The transponder key amplifier coil built into the engine switch is shorted (determined by communication with certification ECU (smart key ECU assembly)).
  • Engine switch
  • Certification ECU (smart key ECU assembly)
  • Wire harness or connector

DTC output confirmation operation:

  • With the shift lever in P and the electrical key transmitter sub-assembly held near the engine switch, an engine start operation is performed by pressing and holding the engine switch when the transmitter battery is depleted.
  • *1: Only output while a malfunction is present.
DTC Detection Conditions
 

Vehicle Condition

Pattern 1

Pattern 2

Diagnosis Condition

Always

○

○

Malfunction Status

The transponder key amplifier coil built into the engine switch is open (determined by communication with certification ECU (smart key ECU assembly)).

○

-

The transponder key amplifier coil built into the engine switch is shorted (determined by communication with certification ECU (smart key ECU assembly)).

-

○

Detection Time

-

-

Number of Trips

1 trip

1 trip
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 transmitter battery is depleted by holding electrical key transmitter sub-assembly near engine switch and pressing and holding engine switch with shift lever in P

-
Related Data List and Active Test

DTC No.

Data List and Active Test

B2784

-

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.
  • Before replacing the certification ECU (smart key ECU assembly), refer to Registration.

    Click here

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

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Smart Key > Clear DTCs
NEXT

2.

CHECK FOR DTC

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

(b) Check for DTCs.

Click here

Body Electrical > Smart Key > Trouble Codes

OK:

DTC B2784 is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

3.

CHECK ENGINE SWITCH (OUTPUT)

(a) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(Engine Switch)

*b

Waveform

*c

Waveform (detail)

-

-

Measurement Condition:

Tester Connection

Condition

Tool Setting

Specified Condition

F59-8 (CODE) - F59-6 (AGND)

Engine switch off, engine switch pressed with electrical key transmitter sub-assembly 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 transmitter battery before performing this inspection.

OK:

The waveform is similar to that shown in the illustration

NG

REPLACE ENGINE SWITCH

OK

4.

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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

Click here

NEXT

5.

REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID code.

Click here

NEXT

6.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Smart Key > Clear DTCs
NEXT

7.

CHECK FOR DTC

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

(b) Check for DTCs.

Click here

Body Electrical > Smart Key > Trouble Codes

OK:

DTC B2784 is not output.

OK

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

REPLACE ENGINE SWITCH

    Short to GND in Immobiliser System Power Source Circuit (B278A)
    DESCRIPTION When there is a short to GND in the power supply for the transponder key amplifier of the engine switch, the certification ECU (smart key ECU assembly) stores this DTC. DT ...

    Theft Deterrent System Communication Line High Fixation (B279A)
    DESCRIPTION If the communication line (IMI - EFIO) between the ECM and ID code box (immobiliser code ECU) is stuck high, the ECM will store this DTC. DTC No. Detection Item ...

    Other materials:

    Toyota CH-R Service Manual > Navigation System: Illumination Circuit
    DESCRIPTION Power is supplied to the radio and display receiver assembly and steering pad switch assembly illumination when the light control switch is in the tail or head position. WIRING DIAGRAM CAUTION / NOTICE / HINT NOTICE: The vehicle is equipped with a Supplemental Restrain ...

    Toyota CH-R Service Manual > Lighting System: Vehicle Specifications have not been Stored (B2451)
    DESCRIPTION This DTC is output if the vehicle variation information is not written to the headlight ECU sub-assembly LH. The headlight ECU sub-assembly LH outputs DTC B2451. DTC No. Detection Item DTC Detection Condition Trouble Area Note ...

    Toyota C-HR (AX20) 2023-2025 Owner's Manual

    Toyota CH-R Owners Manual

    Toyota CH-R Service Manual

    © 2017-2025 Copyright www.tochr.net
    0.0109