DTC P0504 2AD-FHV

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.

Toyota fault code list DTC P0504

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) Ignition 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


Wiring diagram DTC P0504

Inspection procedure

 

NOTICE:

After replacing the ECM, the new ECM needs registration and initialization.

1.CHECK STOP LIGHT SWITCH

  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
 
OK  
   
2.CHECK STP SIGNAL

Check stp signal

  1. Connect the intelligent tester to the DLC3.

  2. Turn the ignition switch on (IG) and turn the tester ON.

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

  4. Check the result.

     

    OK:

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

 

  OK  
CHECK FOR INTERMITTENT PROBLEMS
 
NG  
   
3.INSPECT STOP LIGHT SWITCH

Inspect stop light switch

  1. Disconnect the A5 stop light switch connector.

  2. Measure the resistance of the stop light switch.

     

    Standard resistance:

    Tester Connection Switch Condition Specified Condition
    1 - 2 Pin not pushed Below 1 ?
    3 - 4 Pin not pushed 10 k? or higher
    1 - 2 Pin pushed 10 k? or higher
    3 - 4 Pin pushed Below 1 ?

  3. Reconnect the stop light switch connector.

 

  NG  
REPLACE STOP LIGHT SWITCH
 
OK  
   
4.CHECK WIRE HARNESS (STOP LIGHT SWITCH - ECM)

Check wire harness (stop light switch - ecm)

  1. Disconnect the A5 stop light switch connector.

  2. Disconnect the A12 ECM connector.

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

     

    Standard resistance:

    Tester Connection Specified Condition
    A5-1 - A12-35 (STP) Below 1 ?
    A5-4 - A12-34 (ST1-) Below 1 ?
    A5-1 or A12-35 (STP) - Body ground 10 k? or higher
    A5-4 or A12-34 (ST1-) - Body ground 10 k? or higher

  4. Reconnect the stop light switch connector.

  5. Reconnect the ECM connector.

 

  NG  
REPAIR OR REPLACE HARNESS AND CONNECTOR
 
OK  
   
REPLACE ECM