Dtc P0504 Brake Switch A / B Correlation

Engine. Lexus Is250, Is220D. Gse20 Ale20
2Ad-Fhv Engine Control System. Lexus Is250, Is220D. Gse20 Ale20

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK STOP LIGHT CIRCUIT

READ VALUE OF INTELLIGENT TESTER (STP SIGNAL)

CHECK STOP LIGHT SWITCH ASSEMBLY

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)

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


DESCRIPTION

In this system, the signals of the duplex type stop light switch (STP and ST1-) are used to judge whether the brake system is abnormal. When signals that indicate depressing and releasing the brake pedal are detected simultaneously, the ECM interprets this as a malfunction of the stop light switch.

HINT:
Normal conditions are shown in the table below.

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 is ON (IG)
(b) Brake pedal is released
(c) STP signal is OFF when ST1- signal is OFF
  1. Short in stop light switch signal circuit
  2. Stop light switch
  3. ECM

WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd System. Dtc P0504 Brake Switch A / B Correlation


INSPECTION PROCEDURE

NOTICE:
After replacing the ECM, the new ECM needs registration (Click here) and initialization (Click here).
1.CHECK STOP LIGHT CIRCUIT

  1. Check if the stop lights turn ON and OFF when the brake pedal is depressed and released.

    OK:
    Stop lights turn ON and OFF normally.


NG
REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT
OK


2.READ VALUE OF INTELLIGENT TESTER (STP SIGNAL)


    Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd 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 intelligent tester ON.

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

  1. Check the result.

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


OK
CHECK FOR INTERMITTENT PROBLEMS
NG


3.CHECK STOP LIGHT SWITCH ASSEMBLY


    Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd System. Dtc P0504 Brake Switch A / B Correlation

  1. Remove the stop light switch.

  1. Measure the resistance of the switch.

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


NG
REPLACE STOP LIGHT SWITCH ASSEMBLY
OK


4.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)


    Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd System. Dtc P0504 Brake Switch A / B Correlation

  1. Disconnect the A22 stop light switch connector.

  1. Disconnect the A49 ECM connector.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    A22-1 - STP (A49-35)
    		Below 1 Ω
    A22-4 - ST1- (A49-34)
    		Below 1 Ω
    A22-1 or STP (A49-35) - Body ground
    		10 kΩ or higher
    A22-4 or ST1- (A49-34) - Body ground
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ECM