Last Modified: 11-20-2023 6.11:8.1.0 Doc ID: RM1000000014URM
Model Year Start: 2018 Model: Camry Prod Date Range: [06/2017 - 10/2020]
Title: PRE-COLLISION: PRE-COLLISION SYSTEM: C1A4B; Stop Light Relay Circuit; 2018 - 2020 MY Camry [06/2017 - 10/2020]

DTC

C1A4B

Stop Light Relay Circuit

DESCRIPTION

The skid control ECU (brake actuator assembly) sends a stop light operation request signal to the stop light relay (stop light switch assembly). If the skid control ECU (brake actuator assembly) detects a malfunction in the stop light relay circuit, the millimeter wave radar sensor assembly stores DTC C1A4B.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C1A4B

Stop Light Relay Circuit

While the ignition switch is ON, the millimeter wave radar sensor assembly receives a stop light relay circuit malfunction signal from the skid control ECU (brake actuator assembly) for 1 second or more.
  • Vehicle stability control system
  • Millimeter wave radar sensor assembly

CAUTION / NOTICE / HINT

NOTICE:

  • When replacing the millimeter wave radar sensor assembly, always replace it with a new one. If a millimeter wave radar sensor assembly which was installed to another vehicle is used, the information stored in the millimeter wave radar sensor assembly will not match the information from the vehicle. As a result, a DTC may be stored.
  • If the millimeter wave radar sensor assembly has been replaced, be sure to perform millimeter wave radar sensor assembly adjustment.

    Click here 2018 - 2020 MY Camry [06/2017 - 10/2020]; CRUISE CONTROL: MILLIMETER WAVE RADAR SENSOR: ADJUSTMENT

  • The pre-collision system uses the CAN communication system. First, confirm that there are no malfunctions in the CAN communication system. Refer to How to Proceed with Troubleshooting.

    Click here 2018 - 2024 MY Camry [03/2017 -        ]; NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING

PROCEDURE

1.

CHECK FOR DTCs (VEHICLE STABILITY CONTROL SYSTEM)

HINT:

Pre-collision system DTC C1A4B may be stored due to a malfunction in the vehicle stability control system. Therefore, it is necessary to check for and troubleshoot vehicle stability control system DTCs first.

(a) Check for DTCs.

Chassis > ABS/VSC/TRAC/EPB > Trouble Codes

Result

Proceed to

Vehicle stability control system DTCs are not output

A

Vehicle stability control system DTCs are output

B
B

GO TO VEHICLE STABILITY CONTROL SYSTEM

  • w/ Electric Parking Brake System: Click here 2018 - 2020 MY Camry [06/2017 - 10/2020]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM (w/ Electric Parking Brake System): HOW TO PROCEED WITH TROUBLESHOOTING
  • w/o Electric Parking Brake System: Click here 2018 - 2020 MY Camry [06/2017 - 10/2020]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM (w/o Electric Parking Brake System): HOW TO PROCEED WITH TROUBLESHOOTING

A

2.

CHECK FOR DTCs (PRE-COLLISION SYSTEM)

(a) Clear the DTCs.

Body Electrical > Pre-Collision 2 > Clear DTCs

(b) Perform the following procedure.

HINT:

If the following procedure is not performed, the previously output DTC cannot be detected.

  1. Turn the ignition switch to ON and wait 1 second or more.

(c) Check for DTCs.

Body Electrical > Pre-Collision 2 > Trouble Codes

Result

Proceed to

DTC C1A4B is not output

A

DTC C1A4B is output

B
A

USE SIMULATION METHOD TO CHECK 2018 MY Camry [06/2017 - 08/2018]; INTRODUCTION: HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS: HOW TO PROCEED WITH TROUBLESHOOTING 2019 MY Camry [08/2018 - 09/2019]; INTRODUCTION: HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS: HOW TO PROCEED WITH TROUBLESHOOTING 2020 MY Camry [09/2019 - 03/2020]; INTRODUCTION: HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS: HOW TO PROCEED WITH TROUBLESHOOTING 2020 MY Camry [03/2020 - 10/2020]; INTRODUCTION: HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS: HOW TO PROCEED WITH TROUBLESHOOTING

B

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY