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

1. Disconnect the stop light switch assembly connector.
   Fig 1: View Of Stop Light Switch Assembly Connector

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A19-2 - Body ground	Always	11 to 14 V

3. Reconnect the stop light switch assembly connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY) 

OK: Go to next step 

1. Disconnect the stop light switch assembly connector.
   Fig 2: View Of Stop Light Switch Assembly Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the ignition switch to ON.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   A19-4 - Body ground	Ignition switch ON	11 to 14 V

4. Reconnect the stop light switch assembly connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - IG2 RELAY) 

OK: Go to next step 

1. Remove the stop light switch assembly.
   Fig 3: Inspecting Stop Light Switch Assembly

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

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

3. Reinstall the stop light switch assembly.

NG → See step   5 

OK: Go to next step 

1. Disconnect the ECM connector.
   Fig 4: Identifying A55 ECM Connector Terminals

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2. Turn the ignition switch to ON.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Brake Pedal Operation	Specified Condition
   A55-35 (ST1-) - Body ground	Released	7.5 to 14 V
   	Depressed	0 to 1.5 V
   A55-36 (STP) - Body ground	Released	0 to 1.5 V
   	Depressed	7.5 to 14 V

4. Reconnect the ECM connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - ECM) 

OK → See step   6