Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Back Door Entry Lock and Unlock Functions do not Operate

Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Smart Access System With Push-button Start (for Entry Function) / Back Door Entry Lock and Unlock Functions do not Operate

DESCRIPTION

If the entry lock and unlock functions do not operate for the back door only, the request code may not be being transmitted from the back door. If the entry functions for other doors operate properly, communication between the electrical key transmitter sub-assembly and door control receiver assembly is normal. In this case, there may be a problem with request code transmission (communication between the certification ECU (smart key ECU assembly) and electrical key antenna (outside luggage compartment)) or there may be wave interference.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • The smart access system with push-button start (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 access system with push-button start (for Entry Function) after confirming that the communication systems are functioning properly.

    Click here

  • 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 Access. 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.
  • Check that there are no electrical key transmitter sub-assemblies in the vehicle.
  • Before replacing the certification ECU (smart key ECU assembly), refer to Precaution.

    Click here

  • After repair, confirm that no DTCs are output.

HINT:

  • If the back door entry lock and unlock functions do not operate, the cause of the malfunction may be stored in the certification ECU (smart key ECU assembly).
  • If the cause of the malfunction is stored in the certification ECU (smart key ECU assembly), the following table is helpful in checking whether the malfunction was caused by wave interference.
Body Electrical > Smart Access > Utility

Tester Display

Operation History
Radio Wave Interference

Parameter Name

Content

Lock / Key RF Signal Interference

When an entry lock operation was performed, the electrical key transmitter sub-assembly could not be confirmed due to wave interference.

If the cause of the malfunction has not been stored but the vehicle has been moved and an entry lock operation has been successfully performed, the possibility of wave interference is high.

Operating Trunk Switch / Key RF Signal Interference

When an entry back door unlock operation was performed, the electrical key transmitter sub-assembly could not be confirmed due to wave interference.

If the cause of the malfunction has not been stored but the vehicle has been moved and a back door unlock operation has been successfully performed, the possibility of wave interference is high.

PROCEDURE

1.

CHECK POWER DOOR LOCK CONTROL SYSTEM

(a) When the door control switch on the multiplex network master switch assembly is operated, check that the doors unlock and lock according to the switch operation.

Click here

OK:

Door locks operate normally.

NG

GO TO POWER DOOR LOCK CONTROL SYSTEM

OK

2.

CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Smart Access > Trouble Codes

Result

Proceed to

DTC B27A8 is not output

A

DTC B27A8 is output

B
B

GO TO DIAGNOSTIC TROUBLE CODE CHART

A

3.

CHECK WAVE ENVIRONMENT

(a) Bring the electrical key transmitter sub-assembly approximately 0.3 m (0.984 ft.) from the electrical key antenna (outside luggage compartment) and perform an entry back door open/lock function check.

Click here

  • Communication may not be possible if the electrical key transmitter sub-assembly is within 0.2 m (0.656 ft.) of the electrical key antenna (outside luggage compartment)
  • When the electrical key transmitter sub-assembly is brought near the electrical key antenna (outside luggage compartment), the possibility of wave interference decreases, and it can be determined if wave interference is causing the problem symptom.
  • If the inspection result is that the problem only occurs in certain locations or at certain times of day, the possibility of wave interference is high. Also, added vehicle components may cause wave interference. If installed, remove them and perform the operation check.
  • There may be wave interference if the vehicle is near broadcasting antennas, large video displays, wireless garage door opener systems, wireless security cameras, home security systems, etc. In this case, move the vehicle to a different location and check if there is any improvement.
  • If a tool for checking radio waves, such as a signal strength meter, is available, move around the area while observing both the LF band (used by the vehicle antenna to form the detection area) and RF band (used by the electrical key transmitter sub-assembly for transmission) to check for locations where there is wave interference.
  • When checking the operation of the entry lock function several times, it can be operated up to 2 times consecutively. To operate the function 3 times or more consecutively, the doors need to be unlocked once. However, this is only for the entry lock function, other door lock operations, such as a wireless door lock operation can be performed consecutively.

*a

Approximately 0.3 m (0.984 ft.)

Result

Proceed to

Entry function does not operate normally

A

Entry function operates normally

B
B

AFFECTED BY WAVE INTERFERENCE
A

4.

READ VALUE USING TECHSTREAM (TR/B DOOR LOCK SW, TR/B DOOR UNLOCK SW)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Smart Access / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Tr/B-Door Lock SW

Back door opener switch assembly (lock switch)

ON or OFF

ON: Back door opener switch assembly (lock switch) pressed

OFF: Back door opener switch assembly (lock switch) not pressed
  • Displays whether the back door opener switch assembly (lock switch) is on or off.
  • Use this Data List item to help determine if there is a switch malfunction when the back door lock function does not operate.

Tr/B-Door Unlock SW

Back door opener switch assembly (open switch)

ON or OFF

ON: Back door opener switch assembly (open switch) pressed

OFF: Back door opener switch assembly (open switch) not pressed
  • Displays whether the back door opener switch assembly (open switch) is on or off.
  • Use this Data List item to help determine if there is a switch malfunction when the back door open function does not operate.
Body Electrical > Smart Access > Data List

Tester Display

Tr/B-Door Lock SW

Tr/B-Door Unlock SW

OK:

The Techstream display changes correctly in response to the operation of the back door opener switch assembly.

NG

GO TO STEP 9

OK

5.

CHECK KEY DIAGNOSTIC MODE

(a) Check the following antenna in key diagnostic mode.

Body Electrical > Smart Access > Utility

Tester Display

Communication Check(Key Diag Mode)

(b) Select either channel 1 or channel 2 and perform the key diagnostic mode inspection for each channel.

(1) Check the electrical key antenna (outside luggage compartment):

When the electrical key transmitter sub-assembly is brought within 0.7 to 1 m (2.30 to 3.28 ft.) of the electrical key antenna (outside luggage compartment), check that the wireless buzzer sounds.

HINT:

  • Select either channel 1 or channel 2 and perform the key diagnostic mode inspection for each channel.
  • If the buzzer sounds with [CH1] displayed but not with [CH2], the electrical key transmitter sub-assembly cannot be detected by channel 2 due to a malfunction, such as wave interference.

*a

0.7 to 1 m (2.30 to 3.28 ft.)

Result

Proceed to

Wireless buzzer does not sound

A

Wireless buzzer sounds

B
B

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

A

6.

CHECK HARNESS AND CONNECTOR (ELECTRICAL KEY ANTENNA (OUTSIDE LUGGAGE COMPARTMENT) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Disconnect the R1 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the W1 electrical key antenna (outside luggage compartment) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

R1-13 (CLG8) - W1-2 (ANTE8)

Always

Below 1 Ω

R1-12 (CG8B) - W1-1 (CLGB)

Always

Below 1 Ω

R1-13 (CLG8) or W1-2 (ANTE8) - Body ground

Always

10 kΩ or higher

R1-12 (CG8B) or W1-1 (CLGB) - Body ground

Always

10 kΩ or higher

(d) Reconnect the W1 electrical key antenna (outside luggage compartment) connector.

(e) Reconnect the R1 certification ECU (smart key ECU assembly) connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

7.

INSPECT CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (OUTPUT TO ELECTRICAL KEY ANTENNA (OUTSIDE LUGGAGE COMPARTMENT))

(a) 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

R1-13 (CLG8) - J41-18 (E)

Procedure:

  1. Engine switch off
  2. Electrical key transmitter sub-assembly brought outside vehicle
  3. All doors closed
  4. Back door opener switch assembly off → on

2 V/DIV., 500 ms/DIV.

Pulse generation

(See waveform 1)

R1-12 (CG8B) - J41-18 (E)

Procedure:

  1. Engine switch off
  2. Electrical key transmitter sub-assembly brought outside vehicle
  3. All doors closed
  4. Back door opener switch assembly off → on

2 V/DIV., 500 ms/DIV.

Pulse generation

(See waveform 1)
OK

REPLACE ELECTRICAL KEY ANTENNA (OUTSIDE LUGGAGE COMPARTMENT)

NG

8.

CHECK ENTRY LOCK OPERATION

(a) Connect all connectors and check that the function operates normally.

Click here

Result

Proceed to

Entry function does not operate normally

A

Entry function operates normally

B
A

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

B

END (CONNECTOR WAS NOT CONNECTED SECURELY)

9.

CHECK HARNESS AND CONNECTOR (BACK DOOR OPENER SWITCH ASSEMBLY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) AND BODY GROUND)

(a) Disconnect the R1 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the Z8 back door opener switch assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

R1-27 (TSW6) - Z8-1 (L)

Always

Below 1 Ω

R1-26 (TSW5) - Z8-3 (UL)

Always

Below 1 Ω

Z8-2 (E) - Body ground

Always

Below 1 Ω

R1-27 (TSW6) or Z8-1 (L) - Body ground

Always

10 kΩ or higher

R1-26 (TSW5) or Z8-3 (UL) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

10.

INSPECT BACK DOOR OPENER SWITCH ASSEMBLY

(a) Remove the back door opener switch assembly.

Click here

(b) Inspect the back door opener switch assembly.

Click here

NG

REPLACE BACK DOOR OPENER SWITCH ASSEMBLY

OK

11.

CHECK ENTRY LOCK OPERATION

(a) Connect all connectors and check that the function operates normally.

Click here

Result

Proceed to

Entry function does not operate normally

A

Entry function operates normally

B
A

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

B

END (CONNECTOR WAS NOT CONNECTED SECURELY)
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