Toyota Yaris: Smart Key System (for Start Function) / Antenna Coil Circuit Voltage Out of Range (B27841C)

Toyota Yaris XP210 (2020-2022) Reapir and Service Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Smart Key System (for Start Function) / Antenna Coil Circuit Voltage Out of Range (B27841C)

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

B27841C

Antenna Coil Circuit Voltage Out of Range

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*)

  • Engine switch
  • Certification ECU (smart key ECU assembly)
  • Wire harness or connector
  • 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.
  • *: 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 transmitter battery is depleted by holding electrical key transmitter sub-assembly near engine switch and pressing and holding engine switch.

-

Related Data List and Active Test

DTC No.

Data List and Active Test

B27841C

-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When using the GTS with the ignition switch off, connect the GTS to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the GTS and the vehicle begins. Then select the vehicle type under manual mode and enter the following menus: Body Electrical / Smart Key. While using the GTS, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the GTS and the vehicle.
  • The smart key system (for Start Function) 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) after confirming that the communication systems are functioning properly.

    Click here

  • 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.

CHECK CONNECTION OF CONNECTOR

(a) Check that the connectors are properly connected to the engine switch and certification ECU (smart key ECU assembly).

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY

OK

2.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ENGINE SWITCH AND BODY GROUND)

(a) Disconnect the H46 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the H68 engine switch connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

H46-12 (ANT1) - H68-1 (ANT1)

Always

Below 1 Ω

H46-12 (ANT1) or H68-1 (ANT1) - Body ground

Always

10 kΩ or higher

H46-13 (ANT2) - H68-7 (ANT2)

Always

Below 1 Ω

H46-13 (ANT2) or H68-7 (ANT2) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Connect the H46 certification ECU (smart key ECU assembly) connector.

(b) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(Certification ECU (Smart Key ECU Assembly))

*b

Waveform 1

OK:

Tester Connection

Condition

Tool Setting

Specified Condition

H46-12 (ANT1) - H46-29 (E)

Ignition switch off, electrical key transmitter sub-assembly not in cabin, within 30 seconds of engine switch pressed

20 V/DIV., 200 ms./DIV.

Pulse generation

(See waveform 1)

H46-13 (ANT2) - H46-29 (E)

Ignition switch off, electrical key transmitter sub-assembly not in cabin, within 30 seconds of engine switch pressed

20 V/DIV., 200 ms./DIV.

Pulse generation

(See waveform 2)

OK

REPLACE ENGINE SWITCH

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

    Power Source Control System Circuit Short to Battery or Open (B278215)

    DESCRIPTION The certification ECU (smart key ECU assembly) has a power source mode switching function. This DTC is stored when the IGE input (the steering lock motor activation permission signal) sent directly from the certification ECU (smart key ECU assembly) to the steering lock ECU (steering lock actuator or upper bracket assembly) is determined to be abnormal...

    ID-BOX Component Internal Failure (B278D96)

    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, the certification ECU (smart key ECU assembly) stores this DTC...

    Other information:

    Toyota Yaris XP210 (2020-2022) Reapir and Service Manual: Fuel Rail / System Pressure - Too High (P008800)


    DESCRIPTION Refer to DTC P008700. Click here DTC No. Detection Item DTC Detection Condition Trouble Area MIL Note P008800 Fuel Rail / System Pressure - Too High Although the ECM is requesting the fuel pump assembly (for high pressure side) to open the spill control valve, fuel pressure increases 3 MPa (30...

    Toyota Yaris XP210 (2020-2022) Owner's Manual: Fuel Requirements


    Vehicles with catalytic converters or oxygen sensors must use ONLY UNLEADED FUEL, which will reduce exhaust emissions and keep spark plug fouling to a minimum. To achieve maximum engine performance, use the specified fuel. * 1: U.S. federal law requires that octane ratings be posted on gas station pumps...

    Categories

    Key Suspend Function

    If a key is left in the vehicle, the functions of the key left in the vehicle are temporarily suspended to prevent theft of the vehicle.

    To restore the functions, press the unlock button on the functions-suspended key in the vehicle.

    read more

     
    Copyright © 2022 www.toyaris4.com