Last Modified: 11-20-2023 6.11:8.1.0 Doc ID: RM1000000014W9W
Model Year Start: 2018 Model: Camry HV Prod Date Range: [07/2017 - 09/2018]
Title: PRE-COLLISION: PRE-COLLISION SYSTEM: C1A4B; Stop Light Relay Circuit; 2018 MY Camry HV [07/2017 - 09/2018]

DTC

C1A4B

Stop Light Relay Circuit

DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) sends a stop light operation request signal to the stop light relay (stop light switch assembly). If the skid control ECU (brake booster with master cylinder 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 power switch is on (IG), the millimeter wave radar sensor assembly receives a stop light relay circuit malfunction signal from the skid control ECU (brake booster with master cylinder assembly) for 1 second or more.
  • Electronically controlled brake 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 HV [07/2017 - 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 HV [07/2017 -        ]; NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING

PROCEDURE

1.

CHECK FOR DTCs (ELECTRONICALLY CONTROLLED BRAKE SYSTEM)

HINT:

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

(a) Check for DTCs.

Chassis > ABS/VSC/TRAC > Trouble Codes

Result

Proceed to

Electronically controlled brake system DTCs are not output

A

Electronically controlled brake system DTCs are output

B
B

GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM

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 power switch on (IG) 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

B

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY