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

1. Disconnect the stop light switch connector.
   Fig 1: Identifying A1 Stop Light Switch Connector Terminals

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A1-2 - Body ground	Always	11 to 14 V
   A1-3 - Body ground	Ignition switch ON	11 to 14 V

3. Reconnect the stop light switch connector.

NG → See step   4 

OK: Go to next step 

1. Remove the stop light switch.
   Fig 2: Inspecting Stop Light Switch Assembly

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

   Standard Resistance

   Tester Connection	Switch Condition	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.

NG → See step   5 

OK: Go to next step 

1. Disconnect the ECM connector.
   Fig 3: Checking Brake Pedal

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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	Condition	Specified Condition
   A37-35 (ST1-) - Body ground	Brake pedal released	11 to 14 V
   	Brake pedal depressed	0 to 3 V
   A37-36 (STP) - Body ground	Brake pedal released	0 to 3 V
   	Brake pedal depressed	11 to 14 V

4. Reconnect the ECM connector.

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

OK → See step   6 

1. Remove the STOP and IGN fuses from the driver side junction block.
   Fig 4: Identifying STOP And IGN Fuses

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   STOP fuse	Always	Below 1 Ω
   IGN fuse

3. Reinstall the STOP and IGN fuses.

NG → CHECK FOR SHORTS IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE 

OK → REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - STOP LIGHT SWITCH - INTEGRATION RELAY)