Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Stop Light Relay Circuit (C1A4B)

DESCRIPTION

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

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.

  for Gasoline Model with Cornering Light: Click here

  for Gasoline Model without Cornering Light: Click here

PROCEDURE

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

HINT:

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

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

(c) Recheck for DTCs.

HINT:

• DTC C1A4B is stored when a malfunction signal sent from the electronically controlled brake 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 troubleshooting again, even though the DTC was not output when rechecking for DTCs.

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A

GO TO PRE-COLLISION SYSTEM

B

USE SIMULATION METHOD TO CHECK