Last Modified: 07-31-2024 6.11:8.1.0 Doc ID: RM1000000028K9Z
Model Year Start: 2023 Model: GR Corolla Prod Date Range: [11/2022 -           ]
Title: THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): B27841C; Antenna Coil Circuit Voltage Out of Range; 2023 - 2025 MY Corolla Corolla Hatchback GR Corolla [11/2022 -        ]

DTC

B27841C

Antenna Coil Circuit Voltage Out of Range

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

DTC output confirmation operation:

except Manual Transaxle

  • With the shift position 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.

for Manual Transaxle

  • With 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

except Manual Transaxle

  • 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 position in P

for Manual Transaxle

  • 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 Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Start Key(CAN). 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 2023 - 2025 MY Corolla Corolla Hatchback GR Corolla [11/2022 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): HOW TO PROCEED WITH TROUBLESHOOTING

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

    Click here 2023 - 2025 MY Corolla Corolla Hatchback GR Corolla [11/2022 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION

  • 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)

Pre-procedure1

(a) Disconnect the I167 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the I35 engine switch connector.

Procedure1

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I167-12 (ANT1) - I35-1 (ANT1)

Always

Below 1 Ω

I167-12 (ANT1) or I35-1 (ANT1) - Other terminals and body ground

Always

10 kΩ or higher

I167-13 (ANT2) - I35-7 (ANT2)

Always

Below 1 Ω

I167-13 (ANT2) or I35-7 (ANT2) - Other terminals and body ground

Always

10 kΩ or higher

Post-procedure1

(d) None

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

Pre-procedure1

(a) Connect the I167 certification ECU (smart key ECU assembly) connector.

Procedure1

(b) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(Certification ECU (Smart Key ECU Assembly))

*b

Waveform

OK:

Tester Connection

Condition

Tool Setting

Specified Condition

I167-12 (ANT1) - I167-29 (E)

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

5 V/DIV., 200 ms./DIV.

Pulse generation

(See waveform)

I167-13 (ANT2) - I167-29 (E)

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

5 V/DIV., 200 ms./DIV.

Pulse generation

(See waveform)

Post-procedure1

(c) None

OK

REPLACE ENGINE SWITCH

for M20A-FKS: Click here 2019 - 2025 MY Corolla Corolla Hatchback [06/2018 -        ]; M20A-FKS (STARTING): ENGINE SWITCH: REMOVAL

for G16E-GTS: Click here 2023 - 2025 MY GR Corolla [09/2022 -        ]; G16E-GTS (STARTING): ENGINE SWITCH: REMOVAL

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)