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Home >> Lexus >> 2015 >> IS 350 Base, RWD >> Repair and Diagnosis >> Restraints >> Restraints Control Systems >> Pre-Collision System - Diagnostic Codes (1 Of 2) >> Pre-Collision System >> DTC C1A4B: Stop Light Relay Circuit [04/2013 - 08/2015] >> Description
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DTC C1A4B: Stop Light Relay Circuit [04/2013 - 08/2015]: Description

The brake actuator assembly (skid control ECU) sends a stop light operation signal to the semiconductor PWR integration ECU. When the brake actuator assembly (skid control ECU) detects a malfunction in the stop light circuit, the driving support ECU assembly stores DTC C1A4B.

DTC No. Detection Item DTC Detection Condition Trouble Area
C1A4B Stop Light Relay Circuit Either of the following conditions is met:
  • When the engine switch is on (IG), the IG1 terminal voltage is between 11 and 14 V and the stop light illumination output signal (STPO) is output, the signal is not received at terminal STP2 for 0.3 seconds or more.
  • When the engine switch is on (IG), the IG1 terminal voltage is between 11 and 14 V and the stop light illumination output signal (STPO) is not output, the signals received at terminals STP and STP2 are different for 0.3 seconds or more.
  • Lighting system
  • Brake actuator assembly (skid control ECU)
  • Semiconductor PWR integration ECU
  • Harness or connector