Lexus RX (RX 350L, RX450h) 2016-2022 Repair Manual: Stop Light Relay Circuit (C1A4B)

DESCRIPTION

When a stop light relay circuit malfunction signal sent from the vehicle stability control system is detected by the clearance warning ECU assembly, DTC C1A4B is stored.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C1A4B

Stop Light Relay Circuit

Stop light relay circuit malfunction

Vehicle stability control system

CAUTION / NOTICE / HINT

NOTICE:

  • After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

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  • After replacing an ultrasonic sensor or the clearance warning ECU assembly, perform the necessary procedures (adjustment, calibration, initialization or registration).

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  • When DTC C1A4B is stored, there may be a malfunction in the lighting system. Inspect the lighting system before performing the following procedure.

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PROCEDURE

1.

CHECK DTC OUTPUT

(a) Using the Techstream, check for DTCs according to the prompts on the screen.

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HINT:

After turning the engine switch from off to on (IG), wait 4 seconds or more before checking for DTCs.

Body Electrical > Advanced Parking Guidance/ICS/Intuitive P/A > Trouble Codes

(b) Clear the DTCs according to the screen on the Techstream.

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Body Electrical > Advanced Parking Guidance/ICS/Intuitive P/A > Clear DTCs

(c) Recheck for DTCs.

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Body Electrical > Advanced Parking Guidance/ICS/Intuitive P/A > Trouble Codes

HINT:

  • DTC C1A4B is stored when a malfunction signal sent from the vehicle stability control system is detected.
  • If the malfunctioning part has been repaired or replaced before rechecking for DTCs, DTC C1A4B will not be output again.
  • If DTC C1A4B is output frequently, duplicate the conditions that cause the problem symptoms and perform the inspection again, even though the DTC was not output when rechecking for DTCs.

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Result

Proceed to

DTC C1A4B is output

A

DTC C1A4B is not output

B

A

GO TO PRE-COLLISION SYSTEM

B

USE SIMULATION METHOD TO CHECK

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    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

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