Toyota Tacoma (2015-2018) Service Manual: Open in Driver Side Electrical Antenna Circuit (B27A1)

Toyota Tacoma (2015-2018) Service Manual / Door Lock / Smart Key System(for Entry Function) / Open in Driver Side Electrical Antenna Circuit (B27A1)

DESCRIPTION

The certification ECU (smart key ECU assembly) generates a request signal and transmits the signal to the front door outside handle assembly LH [electrical key antenna] at intervals of 0.25 seconds. For the front door outside handle assembly LH [electrical key antenna] to detect when the electrical key transmitter sub-assembly is brought close to the vehicle, a signal requesting a response from the electrical key transmitter sub-assembly is transmitted within approximately 1 m (3.28 ft.) of the driver door at intervals of 0.25 seconds. DTC B27A1 is stored by the certification ECU (smart key ECU assembly) when an open circuit is detected between the certification ECU (smart key ECU assembly) and front door outside handle assembly LH [electrical key antenna] (between terminals CLG1 and ANT1, or terminals CG1B and ANT2).

DTC Code	DTC Detection Condition	Trouble Area	DTC Output Confirmation Operation
B27A1	An open circuit is detected in the circuit between the certification ECU (smart key ECU assembly) and front door outside handle assembly LH (CLG1 - ANT1, CG1B - ANT2) (This is detected by the malfunction detection circuit in the certification ECU (smart key ECU assembly)) (1 trip detection logic*).	Wire harness or connector Front door outside handle assembly LH Certification ECU (smart key ECU assembly)	Any time

*: 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
Entry lock/unlock operation cannot be performed for driver door	-

Related Data List and Active Test

DTC Code	Data List and Active Test
B27A1	Key diagnostic mode can be used to perform troubleshooting

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

The smart key system (for Entry 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 Entry Function) after confirming that the communication systems are functioning properly (See page ).
The smart key system (for Entry 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 Entry Function) after confirming that the communication systems are functioning properly (See page ).
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 smart key system (for Entry Function) Precaution (See page ).
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

PROCEDURE

1.	CHECK CONNECTOR CONNECTION

(a) Turn the engine switch off.

(b) Check that the connectors are properly connected to the certification ECU (smart key ECU assembly) and front door outside handle assembly LH.

OK:

Connectors are properly connected.

CONNECT CONNECTORS PROPERLY

2.	CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - FRONT DOOR OUTSIDEHANDLE ASSEMBLY LH)

(a) Disconnect the C29 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the F40 front door outside handle assembly LH connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
C29-4 (CLG1) - F40-6 (ANT1)	Always	Below 1 Ω
C29-3 (CG1B) - F40-4 (ANT2)	Always	Below 1 Ω
C29-11 (E) - Body ground	Always	Below 1 Ω
C29-4 (CLG1) or F40-6 (ANT1) - Body ground	Always	10 kΩ or higher
C29-3 (CG1B) or F40-4 (ANT2) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (OUTPUT TO DRIVER SIDEELECTRICAL KEY ANTENNA)

(a) Connect the C29 certification ECU (smart key ECU assembly) connector.

Text in Illustration

Component with harness connected

(Certification ECU (smart key ECU assembly))

Waveform 1

Waveform 2

Waveform 3

Waveform 4

(b) Connect the F40 front door outside handle assembly LH connector.

OK:

Tester Connection	Switch Condition	Tool Setting	Specified Condition
C29-4 (CLG1) - C29-11 (E)	Procedure: Engine switch off All doors closed Electrical key transmitter sub-assembly not inside vehicle All doors locked through wireless operation (electrical key transmitter sub-assembly brought inside detection area*)	5 V/DIV., 500 ms./DIV.	Pulse generation (See waveform 1)
C29-4 (CLG1) - C29-11 (E)	Procedure: Engine switch off All doors closed Electrical key transmitter sub-assembly not inside vehicle All doors locked through wireless operation (electrical key transmitter sub-assembly brought outside detection area*)	5 V/DIV., 100 ms./DIV.	Pulse generation (See waveform 2)
C29-3 (CG1B) - C29-11 (E)	Procedure: Engine switch off All doors closed Electrical key transmitter sub-assembly not inside vehicle All doors locked through wireless operation (electrical key transmitter sub-assembly brought inside detection area*)	5 V/DIV., 500 ms./DIV.	Pulse generation (See waveform 3)
C29-3 (CG1B) - C29-11 (E)	Procedure: Engine switch off All doors closed Electrical key transmitter sub-assembly not inside vehicle All doors locked through wireless operation (electrical key transmitter sub-assembly brought inside detection area*)	5 V/DIV., 100 ms./DIV.	Pulse generation (See waveform 4)

*: For details about the entry function detection area, refer to Operation Check (See page ).

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

4.	REPLACE FRONT DOOR OUTSIDE HANDLE ASSEMBLY LH

(a) Temporarily replace the front door outside handle assembly LH with a new or known good one (See page ).

CLEAR DTC

(a) Clear the DTCs (See page ).

6.	CHECK FOR DTC

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

OK:

DTC B27A1 is not output.

END (FRONT DOOR OUTSIDE HANDLE ASSEMBLY LH WAS DEFECTIVE)

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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