DTC P0504 Brake Switch "A" / "B" Correlation; DTC P0724 Brake Switch "B" Circuit High: Wiring Diagram

Fig 1: Wiring Diagram - Brake Switch

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HINT:

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction (See FREEZE FRAME DATA  ).

1. CHECK STOP LIGHT (OPERATION OF STOP LIGHT) 
   1. Check whether the stop lights turn on and off normally when the brake pedal is depressed and released.

      OK: Stop lights turn ON when brake pedal is depressed. 

   NG : REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT 

   OK : GO TO NEXT STEP 

2. READ VALUE OF INTELLIGENT TESTER (STP SIGNAL AND ST1 - VOLTAGE) 
   1. Connect the intelligent tester to the DLC3.
   2. Turn the engine switch on (IG) and turn the tester on.
   3. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / STOP LIGHT SW.
   4. Check the STP signal when the brake pedal is depressed and released.

      OK 

      BRAKE PEDAL POSITION AND SPECIFIED CONDITION
      
      

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

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

      Standard voltage 

      VOLTAGE SPECIFICATION
      
      

      Tester Connection	Brake Pedal Operation	Specified Condition
      ST1- (A5-8) - E1 (E4-7)	Depressed	Below 1.5 V
      ST1- (A5-8) - E1 (E4-7)	Released	7.5 to 14 V

      Fig 2: Depressing And Releasing Brake Pedal

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK : CHECK FOR INTERMITTENT PROBLEMS 

   NG : GO TO NEXT STEP 

3. INSPECT STOP LIGHT SWITCH ASSEMBLY 
   1. Remove the stop light switch assembly.
   2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      RESISTANCE SPECIFICATION
      
      

      Switch Position	Tester Connection	Specified Condition
      Switch pin free	1 - 2	Below 1 Ω
      Switch pin free	3 - 4	10 kΩ or higher
      Switch pin pushed in	1 - 2	10 kΩ or higher
      Switch pin pushed	in 3 - 4	Below 1 Ω

      Fig 3: Inspecting Stop Light Switch Assembly

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   3. Reinstall the stop light switch assembly.

   NG : REPLACE STOP LIGHT SWITCH ASSEMBLY 

   OK : GO TO NEXT STEP 

4. CHECK ECM (STP, ST1 - VOLTAGE) 
   1. Disconnect the A5 and A6 ECM connectors.
   2. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      VOLTAGE SPECIFICATION
      
      

      Tester Connection	Brake Pedal Operation	Specified Condition
      STP (A6-4) - Body ground	Depressed	9 to 14 V
      STP (A6-4) - Body ground	Released	0 to 3 V
      ST1- (A5-8) - Body ground	Depressed	0 to 3 V
      ST1- (A5-8) - Body ground	Released	9 to 14 V

      Fig 4: Identifying A5 And A6 ECM Connectors

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 

   OK : REPLACE ECM