Dtc P0571 Stop Light Switch Circuit Malfunction


DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)

INSPECT FUSE (STOP, IGN)

INSPECT STOP LIGHT SWITCH ASSEMBLY

CHECK HARNESS AND CONNECTOR (BATTERY - STOP LIGHT SWITCH)

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)

DTC P0571 Stop Light Switch Circuit Malfunction


DESCRIPTION

When the brake pedal is depressed, the stop light switch sends a signal to the ECM. When the ECM receives this signal, it cancels the cruise control. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. The cancellation condition occurs when voltage is applied to terminal STP. When the brake is applied, voltage is applied to terminal STP of the ECM through the STOP fuse and the stop light switch, and the ECM turns the cruise control off.

DTC Code
DTC Detection Condition
Trouble Area
P0571
When the voltage of the STP terminal and the ST1- terminal of the ECM is below 1 V for 0.5 sec. or more.
  1. Stop light switch assembly
  2. Stop light switch circuit
  3. ECM

WIRING DIAGRAM


Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.Cruise Control.Cruise Control System. Dtc P0571 Stop Light Switch Circuit Malfunction


INSPECTION PROCEDURE

1.READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)

  1. Using the intelligent tester, read the Data List.

    Cruise Control
    Tester Display
    		Measurement Item / Range
    		Normal Condition
    		Diagnostic Note
    Stop Light SW M-CPU
    		Stop light switch signal (Main CPU) / ON or OFF
    		ON: Brake pedal depressed
    OFF: Brake pedal released
    		-
    OK:
    Display changes according to brake pedal operation described in above table.


NG
Go to step 2
OK

REPLACE ECM

2.INSPECT FUSE (STOP, IGN)

  1. Disconnect the STOP and IGN fuses from the driver side junction block.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    STOP fuse
    		Always
    		Below 1 Ω
    IGN fuse


NG
REPLACE FUSE
OK


3.INSPECT STOP LIGHT SWITCH ASSEMBLY


    Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.Cruise Control.Cruise Control System. Dtc P0571 Stop Light Switch Circuit Malfunction

  1. Remove the stop light switch.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    1 - 2
    		Pin pushed
    		10 kΩ or higher
    Pin not pushed
    		Below 1 Ω
    3 - 4
    		Pin pushed
    		Below 1 Ω
    Pin not pushed
    		10 kΩ or higher


NG
REPLACE STOP LIGHT SWITCH ASSEMBLY
OK


4.CHECK HARNESS AND CONNECTOR (BATTERY - STOP LIGHT SWITCH)
Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.Cruise Control.Cruise Control System. Dtc P0571 Stop Light Switch Circuit Malfunction

  1. Disconnect the S14 stop light switch connector.

  1. Measure the voltage according to the value(s) in the table below.

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    S14-2 - Body ground
    		Always
    		11 to 14 V
    S14-3 - Body ground
    		Ignition switch ON


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


5.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)
Toyota Fortuner. Ggn50, 60 Kun51, 61 Tgn51 Lan50.Cruise Control.Cruise Control System. Dtc P0571 Stop Light Switch Circuit Malfunction

  1. Disconnect the S14 stop light switch connector.

  1. Disconnect the E14*1 or E5*2 ECM connector.

    1. *1: for 1GR-FE
    2. *2: for 1KD-FTV

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    for 1GR-FE:
    Tester Connection
    		Condition
    		Specified Condition
    S14-1 - E14-15 (STP)
    		Always
    		Below 1 Ω
    S14-1 - Body ground
    		Always
    		10 kΩ or higher
    S14-4 - E14-16 (ST1-)
    		Always
    		Below 1 Ω
    S14-4 - Body ground
    		Always
    		10 kΩ or higher
    for 1KD-FTV:
    Tester Connection
    		Condition
    		Specified Condition
    S14-1 - E5-15 (STP)
    		Always
    		Below 1 Ω
    S14-1 - Body ground
    		Always
    		10 kΩ or higher
    S14-4 - E5-14 (ST1-)
    		Always
    		Below 1 Ω
    S14-4 - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE FUSE