Dtc P0504 Brake Switch A / B Correlation


DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT STOP LIGHT SWITCH ASSEMBLY (B+ VOLTAGE)

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND)

INSPECT ECM (STP AND ST1- VOLTAGE)

CHECK HARNESS OR CONNECTOR (ECM - STOP LIGHT SWITCH)

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


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 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 stores the DTC.

HINT:
The normal signal conditions are as shown in the table below.

Signal (ECM Terminal)
Brake Pedal Released
In Transition
Brake Pedal Depressed
STP
OFF
ON
ON
ST1-
ON
ON
OFF
  1. [OFF] denotes ground potential.
  2. [ON] denotes battery potential (+B).
  3. On the GTS, the Data List items Stop Light Switch and ST1 are both ON when the brake pedal is depressed because the characteristics of ST1 indication are the opposite of the characteristics of Stop Light Switch indication.

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) Ignition switch is ON.
(b) Brake pedal is released.
(c) STP signal is OFF when the ST1- signal is OFF.
  1. Open or short in stop light switch signal circuit
  2. Stop light switch assembly
  3. ECM

WIRING DIAGRAM


Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.2Tr-Fe Engine Control.Sfi System. Dtc P0504 Brake Switch A / B Correlation


INSPECTION PROCEDURE

NOTICE:
Inspect the fuses of circuits related to this system before performing the following inspection procedure.
HINT:
  1. Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, 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.
  2. Stop light switch conditions can be checked using the GTS.
    1. Connect the GTS to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the GTS on.
    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light Switch and ST1.
    5. Check the Data List indication when the brake pedal is depressed and released.

Brake Pedal Operation
Stop Light Switch
ST1
Depressed
ON
ON
Released
OFF
OFF
1.INSPECT STOP LIGHT SWITCH ASSEMBLY (B+ VOLTAGE)
Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.2Tr-Fe Engine Control.Sfi System. Dtc P0504 Brake Switch A / B Correlation

  1. Disconnect the stop light switch connector.

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

    Standard Voltage:
    Tester Connection
    		Condition
    		Specified Condition
    A85-1 (B) - Body ground
    		Always
    		11 to 14 V
    A85-5 (B) - Body ground
    		Ignition switch ON
    		11 to 14 V
    Text in Illustration
    *a
    		Front view of wire harness connector
    (to Stop Light Switch Assembly)


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - NO.1 INTEGRATION RELAY, BATTERY)
OK


2.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND)

  1. Disconnect the stop light switch assembly connector.

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

Standard Resistance:
Tester Connection
Condition
Specified Condition
A85-3 (GND) - Body ground
Always
Below 1 Ω


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3.INSPECT ECM (STP AND ST1- VOLTAGE)

Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.2Tr-Fe Engine Control.Sfi System. Dtc P0504 Brake Switch A / B Correlation

  1. Disconnect the ECM connector.

  1. Turn the ignition switch to ON.

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

    Standard Voltage:
    Tester Connection
    		Condition
    		Specified Condition
    G180-11 (ST1-) - Body ground
    		Brake pedal released
    		11 to 14 V
    Brake pedal depressed
    		Below 1.5 V
    G181-10 (STP) - Body ground
    		Brake pedal released
    		Below 1.5 V
    Brake pedal depressed
    		11 to 14 V
    Text in Illustration
    *a
    		Depressed
    *b
    		Released
    *c
    		Rear view of wire harness connector
    (to ECM)


NG
Go to step 4
OK

REPLACE ECM (LandCruiser RM000000VW203EX.html)

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

  1. Disconnect the stop light switch assembly connector.

  1. Disconnect the ECM connector.

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

Standard Resistance:
Tester Connection
Condition
Specified Condition
A85-2 (L) - G180-10 (STP)
Always
Below 1 Ω
A85-4 (L) - G180-11 (ST1-)
Always
Below 1 Ω
A85-2 (L) or G180-10 (STP) - Body ground
Always
10 kΩ or higher
A85-4 (L) or G181-11 (ST1- ) - Body ground
Always
10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE STOP LIGHT SWITCH ASSEMBLY (LandCruiser RM000003QJT01GX.html)