DTC C1A4B: Stop Light Relay Circuit [07/2015 - ]: Description

The brake actuator assembly (skid control ECU) sends a stop light operation request signal to the engine room junction block assembly (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.	DTC Detection Condition	Trouble Area
C1A4B	Diagnosis condition: When the engine switch is on (IG) and the pre-collision brake control is operating, either of the following conditions is met: Malfunction condition: Either of the following conditions is met: When the voltage at the IG1 terminal is between 11 V and 14 V and the stop light illumination output (STPO) signal is on, a signal has not been input to the STP2 terminal continuously for 0.3 seconds or more. When the voltage at the IG1 terminal is between 11 V and 14 V and the stop light illumination output (STPO) signal is off, the input signals at the STP terminal and STP2 terminal differ continuously for 0.3 seconds or more.	Lighting system Wire harness or connector Brake actuator assembly (skid control ECU) Engine room junction block assembly (stop light relay)