Toyota Tacoma manuals

Toyota Tacoma (2015-2018) Service Manual: Open in Front Floor Electrical Key Oscillator Circuit (B27A5)

Toyota Tacoma (2015-2018) Service Manual / Door Lock / Smart Key System(for Entry Function) / Open in Front Floor Electrical Key Oscillator Circuit (B27A5)

DESCRIPTION

The certification ECU (smart key ECU assembly) generates a request signal and transmits the signal to the No. 1 indoor electrical key antenna assembly (front floor). For the No. 1 indoor electrical key antenna assembly (front floor) to detect when the electrical key transmitter sub-assembly is inside the vehicle, the signal from the certification ECU (smart key ECU assembly) requesting a response from the electrical key transmitter sub-assembly is transmitted inside the vehicle. DTC B27A5 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 No. 1 indoor electrical key antenna assembly (front floor) (between terminals CLG5 and CLG, or terminals CG5B and CLGB).

DTC Code

DTC Detection Condition

Trouble Area

DTC Output Confirmation Operation

B27A5

An open circuit is detected in the circuit between the certification ECU (smart key ECU assembly) and No. 1 indoor electrical key antenna assembly (front floor) (CLG5 - CLG, CG5B - CLGB)

(1 trip detection logic*).
  • Wire harness or connector
  • No. 1 indoor electrical key antenna assembly (front floor)
  • 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

When electrical key transmitter sub-assembly is in front seat area:

  • Power source mode does not change when engine switch pressed
  • Electrical key transmitter sub-assembly locked inside vehicle

-
Related Data List and Active Test

DTC Code

Data List and Active Test

B27A5

Key diagnostic mode can be used to perform troubleshooting

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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 When using the Techstream with the engine switch off, connect the Techstream ).
  • 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 ).
  • 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 No. 1 indoor electrical key antenna assembly (front floor).

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY
OK

2.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - NO. 1 INDOORELECTRICAL KEY ANTENNA ASSEMBLY)

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

(b) Disconnect the N29 No. 1 indoor electrical key antenna assembly (front floor) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

C29-21 (CLG5) - N29-1 (CLG)

Always

Below 1 Ω

C29-20 (CG5B) - N29-3 (CLGB)

Always

Below 1 Ω

C29-11 (E) - Body ground

Always

Below 1 Ω

C29-21 (CLG5) or N29-1 (CLG) - Body ground

Always

10 kΩ or higher

C29-20 (CG5B) or N29-3 (CLGB) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (OUTPUT TO NO. 1 INDOORELECTRICAL KEY ANTENNA ASSEMBLY)

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

Text in Illustration

*a

Component with harness connected

(Certification ECU (smart key ECU assembly))

*b

Waveform 1

*c

For 30 seconds after closing any door using the door outside handle

*d

30 seconds or more have elapsed after closing any door using the door outside handle

(b) Connect the N29 No. 1 indoor electrical key antenna assembly (front floor) connector.

(c) Using an oscilloscope, check the waveform.

OK:

Tester Connection

Switch Condition

Tool Setting

Specified Condition

C29-21 (CLG5) - C29-11 (E)
Procedure:
  1. Engine switch off
  2. Electrical key transmitter sub-assembly not inside vehicle
  3. Within 30 seconds of closing any door using the door outside handle

2 V/DIV., 500 ms./DIV.

Pulse generation

(See waveform 1)

C29-20 (CG5B) - C29-11 (E)
Procedure:
  1. Engine switch off
  2. Electrical key transmitter sub-assembly not inside vehicle
  3. Within 30 seconds of closing any door using the door outside handle

2 V/DIV., 500 ms./DIV.

Pulse generation

(See waveform 1)
NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

OK

4.

REPLACE NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR)

(a) Temporarily replace the No. 1 indoor electrical key antenna assembly (front floor) with a new or known good one (See page ).

NEXT

5.

CLEAR DTC

(a) Clear the DTCs (See page ).

NEXT

6.

CHECK FOR DTC

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

OK:

DTC B27A5 is not output.

OK

END (NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR) WAS DEFECTIVE)
NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

All Door Entry Lock/Unlock Functions do not Operate, but Wireless Functions Operate
DESCRIPTION When the wireless operation can be used to lock and unlock the doors, communication between the electrical key and TPMS receiver assembly and certification ECU (smart key ECU assembly ...

Driver Side Door Entry Lock and Unlock Functions do not Operate
DESCRIPTION If the entry lock and unlock functions do not operate for the driver door only, the request code may not be being transmitted from the driver door or the front door outside handle ass ...

Other materials:

Inspection
INSPECTION PROCEDURE 1. INSPECT FUEL INJECTOR ASSEMBLY (a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition 1 - 2 20°C (68°F) 11.6 ...

Tire Pressure Warning Receiver
Components COMPONENTS ILLUSTRATION Removal REMOVAL PROCEDURE 1. SEPARATE ROOF HEADLINING ASSEMBLY (for Double Cab) (See page ) 2. SEPARATE ROOF HEADLINING ASSEMBLY (for Access Cab) (See page ) 3. REMOVE TIRE PRESSURE WARNING ECU AND RECEIVER (a) Disconnect the connector. (b) ...

Data List / Active Test
DATA LIST / ACTIVE TEST 1. READ DATA LIST HINT: Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or sig ...

© 2011-2026 Copyright www.ttguide.net