Toyota CH-R Service Manual: Stop Light Relay Circuit (C1A4B)

Toyota CH-R Service Manual / Pre-collision / Pre-collision System / Stop Light Relay Circuit (C1A4B)

DESCRIPTION

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

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C1A4B	Stop Light Relay Circuit	Diagnosis condition: Ignition switch ON and battery voltage between 11 and 14 V Malfunction condition: Either of the following conditions is met: When the stop light illumination output (STPO) signal is on, a signal has not been input to the STP2 terminal for 0.3 seconds or more continuously. When the stop light illumination output (STPO) signal is off, signals input to the STP terminal and STP2 terminal of the skid control ECU (brake actuator assembly) differ for 0.3 seconds or more continuously.	Vehicle stability control system Millimeter wave radar sensor assembly Skid control ECU (Brake actuator assembly)

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C1A4B

Stop Light Relay Circuit

Diagnosis condition:

Ignition switch ON and battery voltage between 11 and 14 V

Malfunction condition:

Either of the following conditions is met:

When the stop light illumination output (STPO) signal is on, a signal has not been input to the STP2 terminal for 0.3 seconds or more continuously.
When the stop light illumination output (STPO) signal is off, signals input to the STP terminal and STP2 terminal of the skid control ECU (brake actuator assembly) differ for 0.3 seconds or more continuously.

Vehicle stability control system
Millimeter wave radar sensor assembly
Skid control ECU (Brake actuator assembly)

DTC Detection Conditions:

		Vehicle Condition
		Pattern 1	Pattern 2
Diagnosis Condition	Ignition switch to ON and battery voltage between 11 and 14 V.	○	○
Malfunction Status	When the stop light illumination output (STPO) signal is on, a signal has not been input to the STP2 terminal.	○	-
Malfunction Status	When the stop light illumination output (STPO) signal is off, signals input to the STP terminal and STP2 terminal of the skid control ECU (brake actuator assembly).	-	○
Detection Time		0.3 seconds	0.3 seconds
Number of Trips		1 trip	1 trip

HINT:

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.	CHECK FOR DTCs (VEHICLE STABILITY CONTROL SYSTEM)

HINT:

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

(a) Check for DTCs.

Click here

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

GO TO VEHICLE STABILITY CONTROL SYSTEM

2.	CHECK FOR DTCs (PRE-COLLISION SYSTEM)

(a) Clear the DTCs.

Click here

Body Electrical > Pre-Collision 2 > Clear DTCs

(b) Make sure that the DTC detection conditions are met.

HINT:

If the detection conditions are not met, the system cannot detect the malfunction.

Click here

Body Electrical > Pre-Collision 2 > Trouble Codes

Result	Proceed to
DTC C1A4B is output	A
DTC C1A4B is not output	B

USE SIMULATION METHOD TO CHECK

3.	REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY

(a) Replace the millimeter wave radar sensor assembly.

Click here

(b) Adjust the millimeter wave radar sensor assembly.

Click here

4.	CHECK FOR DTCs (PRE-COLLISION SYSTEM)

HINT:

After performing the radar sensor beam axis adjustment, if the same DTC is output again after the DTC detection conditions are met, replace the millimeter wave radar sensor assembly.

(a) Clear the DTCs.

Click here

Body Electrical > Pre-Collision 2 > Clear DTCs

(b) Make sure that the DTC detection conditions are met.

HINT:

If the detection conditions are not met, the system cannot detect the malfunction.

Click here

Body Electrical > Pre-Collision 2 > Trouble Codes

Result	Proceed to
DTC C1A4B is not output	A
DTC C1A4B is output	B

END (MILLIMETER WAVE RADAR SENSOR ASSEMBLY WAS DEFECTIVE)

REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)

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