Toyota Tundra Service Manual: Brake Switch "A" Circuit (P0571)

DESCRIPTION

When the brake pedal is depressed, the stop light switch assembly sends a signal to the ECM. Upon receiving the signal, the ECM cancels the cruise control system.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

P0571

Brake Switch "A" Circuit

When voltage of STP terminal and that of ST1- terminal of ECM are less than 1 V for 0.5 seconds or more

  • Stop light switch assembly
  • ECM
  • Harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • Before replacing the ECM, refer to Registration.

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PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY)

(a) Disconnect the stop light switch assembly connector.

*a

Front view of wire harness connector

(to Stop Light Switch Assembly)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A4-2 - Body ground

Always

11 to 14 V

A4-4 - Body ground

Ignition switch ON

11 to 14 V

A4-4 - Body ground

Ignition switch off

Below 1 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

2.

INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Remove the stop light switch assembly.

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(b) Inspect the stop light switch assembly.

Click here

NG

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK

3.

CHECK HARNESS AND CONNECTOR (ECM - STOP LIGHT SWITCH ASSEMBLY)

(a) Disconnect the ECM connector.

*a

Front view of wire harness connector

(to ECM)

*1

for 1UR-FE

*2

for 3UR-FE

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

Standard Voltage (for 1UR-FE):

Tester Connection

Condition

Specified Condition

A24-35 (ST1-) - Body ground

Ignition switch ON, brake pedal depressed

0 to 1.5 V

Ignition switch ON, brake pedal released

7.5 to 14 V

A24-36 (STP) - Body ground

Brake pedal depressed

7.5 to 14 V

Brake pedal released

0 to 1.5 V

Standard Voltage (for 3UR-FE):

Tester Connection

Condition

Specified Condition

A24-8 (ST1-) - Body ground

Ignition switch ON, brake pedal depressed

0 to 1.5 V

Ignition switch ON, brake pedal released

7.5 to 14 V

A24-7 (STP) - Body ground

Brake pedal depressed

7.5 to 14 V

Brake pedal released

0 to 1.5 V

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

    How To Proceed With Troubleshooting

    Cruise Control Input Circuit (P0575)

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