Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Buzzer Circuit Short to Battery (C1A4A12)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Engine & Hybrid System / Cruise Control / Front Camera System / Buzzer Circuit Short to Battery (C1A4A12)

DESCRIPTION

If the forward recognition camera detects a short to +B in the buzzer circuit, it will store DTC C1A4A12.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C1A4A12

Buzzer Circuit Short to Battery

While the skid control buzzer assembly is sounding, the forward recognition camera detects a short to +B in the buzzer circuit for 3 seconds or more.
  • Skid control buzzer assembly
  • Forward recognition camera
  • Wire harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • When replacing the forward recognition camera, always replace it with a new one. If a forward recognition camera which was installed to another vehicle is used, the information stored in the forward recognition camera will not match the information from the vehicle. As a result, a DTC may be stored.
  • If the forward recognition camera has been replaced with a new one, be sure to perform forward recognition camera adjustment.

    HINT:

    Forward recognition camera adjustment can be performed by using either One Time Recognition or Sequential Recognition.

    One Time Recognition: Click here

    Sequential Recognition: Click here

PROCEDURE

1.

CHECK FOR DTCs

(a) Clear the DTCs.

Chassis > Front Recognition Camera > Clear DTCs

(b) Perform the Active Test according to the display on the Techstream.

NOTICE:

Perform the Active Test for 3 seconds or more.

HINT:

Performing the Active Test for 3 seconds or more causes DTC C1A4A12 to be stored if the DTC detection conditions are met.

Body Electrical > Pre-Collision System > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

PCS Warning Buzzer

Sounds the skid control buzzer

Active / Not Active

Test possible with engine switch on (IG), vehicle stopped
Body Electrical > Pre-Collision System > Active Test

Tester Display

PCS Warning Buzzer

(c) Check for DTCs.

Chassis > Front Recognition Camera > Trouble Codes

Result

Proceed to

DTC C1A4A12 is not output

A

DTC C1A4A12 is output

B
A

USE SIMULATION METHOD TO CHECK

B

2.

CHECK HARNESS AND CONNECTOR (SKID CONTROL BUZZER ASSEMBLY - FORWARD RECOGNITION CAMERA)

(a) Disconnect the A15 skid control buzzer assembly connector.

(b) Disconnect the U14 forward recognition camera connector.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

A15-1 (BZ) or U14-8 (BZ) - Body ground

Engine switch off

Below 1 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

INSPECT SKID CONTROL BUZZER ASSEMBLY

(a) Remove the skid control buzzer assembly.

Click here

(b) Inspect the skid control buzzer assembly.

Click here

OK

REPLACE FORWARD RECOGNITION CAMERA

NG

REPLACE SKID CONTROL BUZZER ASSEMBLY

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