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Home >> Lexus >> 2019 >> LX 570 >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Cruise Control Systems >> Dynamic Radar Cruise Control System (Diagnostic Codes & Circuit Tests) >> Dynamic Radar Cruise Control System >> DTC P0571: Stop Light Switch Circuit [08/2020 - ] >> Description

DTC P0571: Stop Light Switch Circuit [08/2020 - ]: Description

When the brakes are applied by the dynamic radar cruise control system, the skid control ECU (master cylinder solenoid) operates the stop light control relay (STOP LP OPEN relay) to illuminate the stop lights.

Detection condition 1: 

When the brake pedal is depressed, the stop light switch assembly sends a signal to the ECM. When the ECM receives this signal, it cancels the dynamic radar cruise control.

Detection condition 2: 

DTC No. Detection Item DTC Detection Condition Trouble Area
P0571 Brake Switch "A" Circuit Condition1: 
  • When the dynamic radar cruise control system is operating, the ECM detects a signal indicating a stop light control relay (STOP LP OPEN relay) malfunction from the skid control ECU (master cylinder solenoid) for approximately 1 second or more.

Condition 2: 
  • When the dynamic radar cruise control system is operating, the ECM detects that the voltage at terminal STP and ST1- are both less than 1 V for approximately 0.5 seconds or more.
Detection condition 1: 
  1. Vehicle stability control system

Detection condition 2: 
  • Stop light switch assembly
  • Harness or connector
  • ECM