Dtc P0504 Brake Switch A / B Correlation

Engine. Lexus Is250, Is220D. Gse20 Ale20
4Gr-Fse Engine Control System. Lexus Is250, Is220D. Gse20 Ale20

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK STOP LIGHT (STOP LIGHT OPERATION)

READ VALUE OF INTELLIGENT TESTER (STP SIGNAL AND ST1 - VOLTAGE)

INSPECT STOP LIGHT SWITCH ASSEMBLY

CHECK ECM (STP, ST1 - VOLTAGE)

DTC P0504 Brake Switch "A" / "B" Correlation

DTC P0724 Brake Switch "B" Circuit High


DESCRIPTION

The stop light switch is a duplex system that transmits two signals: STP and ST1-. These two signals are used by the ECM to monitor whether or not the brake system is working properly. If the signals, which indicate the brake pedal is being depressed and released, are detected simultaneously, the ECM interprets this as a malfunction in the stop light switch and sets the DTC.

HINT:
The normal conditions are as shown in the table below. The signals can be read using an intelligent tester.

Signal
Brake Pedal Released
In Transition
Brake Pedal Depressed
STP
OFF
ON
ON
ST1-
ON
ON
OFF

DTC No.
DTC Detection Condition
Trouble Area
P0504
Conditions (a), (b) and (c) continue for 0.5 seconds or more
(1 trip detection logic):
(a) Engine switch on (IG)
(b) Brake pedal released
(c) STP signal OFF when ST1- signal OFF
  1. Short in stop light switch signal circuit
  2. Stop light switch
  3. ECM
P0724
The stop light switch remains ON even when the vehicle is driven in a STOP (less than 3 km/h (2 mph)) and GO (30 km/h (19 mph) or more) fashion 5 times. (2 trip detection logic)
  1. Short in stop light switch signal circuit
  2. Stop light switch
  3. ECM

WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0504 Brake Switch A / B Correlation


INSPECTION PROCEDURE

HINT:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred (Click here).
1.CHECK STOP LIGHT (STOP LIGHT OPERATION)

  1. Check whether the stop lights turn on and off normally when the brake pedal is depressed and released.

    OK:
    Stop lights turn ON when brake pedal is depressed.


NG
REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT
OK


2.READ VALUE OF INTELLIGENT TESTER (STP SIGNAL AND ST1 - VOLTAGE)


    Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0504 Brake Switch A / B Correlation

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG) and turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Stop Light Switch.

  1. Check the STP signal when the brake pedal is depressed and released.

    OK:
    Brake Pedal Operation
    		Specified Condition
    Depressed
    		STP signal ON
    Released
    		STP signal OFF

  1. Measure the voltage of the A5 and E4 ECM connectors.

    Standard voltage:
    Tester Connection
    		Brake Pedal Operation
    		Specified Condition
    ST1- (A5-8) - E1 (E4-7)
    		Depressed
    		Below 1.5 V
    ST1- (A5-8) - E1 (E4-7)
    		Released
    		7.5 to 14 V


OK
CHECK FOR INTERMITTENT PROBLEMS
NG


3.INSPECT STOP LIGHT SWITCH ASSEMBLY


    Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0504 Brake Switch A / B Correlation

  1. Remove the stop light switch assembly.

  1. Measure the resistance of the stop light switch.

    Standard resistance:
    Switch Position
    		Tester Connection
    		Specified Condition
    Switch pin free
    		1 - 2
    		Below 1 Ω
    Switch pin free
    		3 - 4
    		10 kΩ or higher
    Switch pin pushed in
    		1 - 2
    		10 kΩ or higher
    Switch pin pushed in
    		3 - 4
    		Below 1 Ω

  1. Reinstall the stop light switch assembly.



NG
REPLACE STOP LIGHT SWITCH ASSEMBLY
OK


4.CHECK ECM (STP, ST1 - VOLTAGE)


    Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Engine Control System.Sfi System. Dtc P0504 Brake Switch A / B Correlation

  1. Disconnect the A5 and A6 ECM connectors.

  1. Measure the voltage of the A5 and A6 ECM connectors.

    Standard voltage:
    Tester Connection
    		Brake Pedal Operation
    		Specified Condition
    STP (A6-4) - Body ground
    		Depressed
    		9 to 14 V
    STP (A6-4) - Body ground
    		Released
    		0 to 3 V
    ST1- (A5-8) - Body ground
    		Depressed
    		0 to 3 V
    ST1- (A5-8) - Body ground
    		Released
    		9 to 14 V


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ECM