DTC C1A4B: Stop Light Relay Circuit [10/2015 - 09/2017]: Description

The brake actuator assembly (skid control ECU) sends a stop light operation request signal to the No. 2 integration relay (stop light relay). If the brake actuator assembly (skid control ECU) detects a malfunction in the stop light relay circuit, the driving support ECU assembly stores DTC C1A4B.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C1A4B	Stop Light Relay Circuit	When the engine switch is on (IG) is operating, 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 brake actuator assembly (skid control ECU) differ for 0.3 seconds or more continuously.	Lighting system Brake actuator assembly (Skid control ECU) No. 2 integration relay (Stop light relay) Wire harness or connector

DTC DETECTION CONDITIONS:

		Vehicle Condition
		Pattern 1	Pattern 2
Diagnosis Condition	Engine switch is on (IG)	◦	◦
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 brake actuator assembly (skid control ECU) differ	-	◦
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.