DTC P0571-11: Brake Switch "A" Circuit Short to Ground [09/2021 - 11/2022]: Procedure

1. Enter the following menus:

   Chassis > Brake/EPB > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   Master Cylinder Sensor 1	Master cylinder pressure sensor pressure (value detected by ECU)	Min.: -1.00 MPa, Max.: 23.99 MPa	Brake pedal released: -1.00 to 0.00 MPa	Reading increases when brake pedal is depressed

   Chassis > Brake/EPB > Data List 

   Tester Display
   Master Cylinder Sensor 1

2. Check the value of Data List item Master Cylinder Sensor 1 when the brake pedal is released.

   OK

   The value of Data List item Master Cylinder Sensor 1 when the brake pedal is released is less than 0.15 MPa.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  4

Result: 

OK 

See step  2

1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

   OK

   The connector is securely connected.

2. Disconnect the skid control ECU (brake actuator assembly) connector.
3. Check both the connector case and the terminals for deformation and corrosion.

   OK

   No deformation or corrosion.

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A151-41 (STP) - Body ground	Brake pedal depressed	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [09/2021 - 11/2022] 

Result: 

NG 

See step  3

1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

   OK

   The connector is securely connected.

2. Disconnect the A151 skid control ECU (brake actuator assembly) connector.
3. Disconnect the A53 stop light switch assembly connector.
4. Check both the connector case and the terminals for deformation and corrosion.

   OK

   No deformation or corrosion.

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A53-3 (L) - A151-41 (STP)	Always	Below 1 Ω
   A53-3 (L) or A151-41 (STP) - Body ground and other terminals	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [09/2021 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

1. Read the DTCs following the prompts on the GTS. Enter the following menus:

   Chassis > Brake/EPB > Trouble Codes 

2. Check the details of the DTCs.

   Result

   Result	Proceed to
   P0571-11 and C0540-1C, C0540-28 and/or C0540-49 are output simultaneously	A
   P0571-11 is output	B

Result: 

A 

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS 

Result: 

B 

GO TO BRAKE SYSTEM 

Inspect brake pedal free play: Refer to ADJUSTMENT [09/2021 - 11/2022]

Inspect brake booster assembly: Refer to ON-VEHICLE INSPECTION [09/2021 - 11/2022]