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

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DESCRIPTION

In this system, the signal of the stop light switch is used to judge whether the acceleration system is abnormal or not.
The stop light switch has a duplex system (signals STP and ST1-) to memorize the abnormality when the signals of depressing and releasing the brake pedal are detected simultaneously.

HINT:
The Normal condition is 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
  1. Conditions (a), (b) and (c) continue for 0.5 sec or more:
    1. (a) Ignition switch ON
    2. (b) Brake pedal released
    3. (c) STP signal is OFF when ST1- signal is OFF
  1. Short in stop light switch signal circuit
  2. STOP fuse
  3. Stop light switch
  4. ECM

WIRING DIAGRAM


A112418E01


INSPECTION PROCEDURE

HINT:
Reed freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is 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.

1.CHECK OPERATION OF STOP LIGHT

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

    OK:
    Stop lights illuminate and turn off.



NG
REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT
OK


2.INSPECT STOP LIGHT SWITCH
A072924E11

  1. Measure the resistance of the switch.

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



NG
REPLACE STOP LIGHT SWITCH
OK


3.READ DATA LIST (STP SIGNAL AND ST1 - VOLTAGE)
A112419E01

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch ON and turn the tester ON.

  1. Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light SW.

  1. Check the result.

    Standard:
    Brake Pedal
    		Specified Condition
    Depressed
    		STP Signal ON
    Released
    		STP Signal OFF

  1. Measure the voltage of the E14 and E17 ECM connectors.

    Standard voltage:
    Tester Connection
    		Brake Pedal
    		Specified Condition
    E14-16 (ST1-) - E17-1 (E1)
    		Depressed
    		Below 1.5 V
    E14-16 (ST1-) - E17-1 (E1)
    		Released
    		7.5 to 14 V



OK
CHECK FOR INTERMITTENT PROBLEMS
NG


4.CHECK WIRE HARNESS (STOP LIGHT SWITCH - ECM)
A112420E01

  1. Disconnect the S14 stop light switch connector.

  1. Disconnect the E14 ECM connector.

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

    Standard resistance:
    Tester Connection
    		Specified Condition
    S14-1 - E14-15 (STP)
    		Below 1 Ω
    S14-4 - E14-16 (ST1-)
    		Below 1 Ω
    S14-1 or E14-15 (STP) - Body ground
    		10 kΩ or higher
    S14-4 or E14-16 (ST1-) - Body ground
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

REPLACE ECM