DTC    P0504/51    Brake Switch "A" / "B" Correlation

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DESCRIPTION

In this system, the signals of the stop light switch's duplex system (STP and ST1-) are used to judge whether the brake system is abnormal or not. When the signals of depressing and releasing the brake pedal are detected simultaneously, the ECM interprets this as a malfunction of the stop light switch.

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

HINT:
The normal condition of the signals is shown in the table above.

DTC No.
DTC Detection Condition
Trouble Area
P0504/51
Conditions (a), (b) and (c) continue for 0.5 seconds 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


A094232E02


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 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.


When using intelligent tester:

1.CHECK STOP LIGHT (OPERATION)

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

    OK:
    Stop lights turn ON and OFF when brake pedal is depressed and released, respectively.



NG
REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT
OK


2.READ DATA LIST (STP SIGNAL, ST1- VOLTAGE)
A079135E02

  1. Connect the intelligent tester to the DLC3.

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

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

  1. Check the STP signal when depressing and releasing the brake pedal.

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

  1. Measure the voltage of the ECM connectors.

    Standard voltage:
    Tester Connection
    		Brake Pedal Condition
    		Specified Condition
    E9-16 (ST1-) - E12-3 (E1)
    		Depressed
    		Below 1.5 V
    E9-16 (ST1-) - E12-3 (E1)
    		Released
    		7.5 to 14 V



OK
CHECK FOR INTERMITTENT PROBLEMS
NG


3.INSPECT STOP LIGHT SWITCH ASSEMBLY
A072924E07

  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 ECM (STOP LIGHT SWITCH - ECM)
G039269E01

  1. Disconnect the E9 and E10 ECM connectors.

  1. Disconnect the S14 stop light switch connector.

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

    Standard resistance:
    Tester Connection
    		Specified Condition
    S14-1 - E10-4 (STP)
    		Below 1 Ω
    S14-4 - E9-16 (ST1-)
    		Below 1 Ω



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

REPLACE ECM 


When not using intelligent tester:

1.CHECK STOP LIGHT (OPERATION)

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

    OK:
    Stop lights turn ON and OFF when brake pedal is depressed and released, respectively.



NG
REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT
OK


2.CHECK ECM (STP, ST1- VOLTAGE)
A079135E05

  1. Turn the ignition switch ON.

  1. Measure the voltage of the ECM connectors.

    Standard voltage:
    Tester Connection
    		Brake Pedal Condition
    		Specified Condition
    E10-4 (STP) - E12-3 (E1)
    		Depressed
    		7.5 to 14 V
    E10-4 (STP) - E12-3 (E1)
    		Released
    		Below 1.5 V
    E9-16 (ST1-) - E12-3 (E1)
    		Depressed
    		Below 1.5 V
    E9-16 (ST1-) - E12-3 (E1)
    		Released
    		7.5 to 14 V



OK
CHECK FOR INTERMITTENT PROBLEMS
NG


3.INSPECT STOP LIGHT SWITCH ASSEMBLY
A072924E07

  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 ECM (STOP LIGHT SWITCH - ECM)
G039269E01

  1. Disconnect the E9 and E10 ECM connectors.

  1. Disconnect the S14 stop light switch connector.

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

    Standard resistance:
    Tester Connection
    		Specified Condition
    S14-1 - E10-4 (STP)
    		Below 1 Ω
    S14-4 - E9-16 (ST1-)
    		Below 1 Ω



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

REPLACE ECM