DTC P0703-12: Brake Switch "B" Circuit Short to Battery [11/2018 - ]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Transmission / Data List / Stop Light SW.
5. Read the Data List according to the display on the Techstream.

   Powertrain > Transmission > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   Stop Light SW	Stop light switch status	ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

   Powertrain > Transmission > Data List 

   Tester Display
   Stop Light SW

   Result

   Result	Proceed to
   Data List value is normal	A
   Data List value is not normal	B

Result: 

A 

SYMPTOM SIMULATION AND DTC CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2018 - ] 

Result: 

B 

See step  2

1. Check the stop light switch assembly installation condition.

   Refer to INSTALLATION [11/2018 - ]

   OK

   Stop light switch assembly is installed correctly.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REINSTALL STOP LIGHT SWITCH ASSEMBLY CORRECTLY. Refer to  INSTALLATION [11/2018 - ] 

Result: 

OK 

See step  3

1. Inspect the stop light switch assembly.

   Refer to ON-VEHICLE INSPECTION [11/2018 - ]

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [11/2018 - ] 

Result: 

OK 

See step  4

1. Disconnect the ECM connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Brake pedal depressed	*b	Brake pedal released
   *c	Front view of wire harness connector (to ECM)	-	-

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A24-21 (STP) - Body ground	Brake pedal released	Below 1.5 V
   	Brake pedal depressed	7.5 to 14 V

   HINT: 

   If there is a short in the STP terminal circuit, there may be a malfunction in the circuit of a connected ECU.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

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

Result: 

OK 

See step  5

1. Replace the ECM.

   Refer to REMOVAL [11/2018 - 08/2020] , or refer to REMOVAL [08/2020 - 10/2022] , or refer to REMOVAL [10/2022 - 10/2023] , or refer to REMOVAL [10/2023 - ]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

PERFORM REGISTRATION. Refer to  REGISTRATION [11/2018 - ]