Toyota Venza manuals

Toyota Venza: Brake Switch "A" Circuit (P0571)

Toyota Venza Service Manual / Cruise Control / Cruise Control System / Brake Switch "A" Circuit (P0571)

DESCRIPTION

When the brake pedal is depressed, the stop light switch assembly sends a signal to the ECM. When the ECM receives this signal, it cancels the cruise control. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. Cruise control cancellation occurs when voltage is applied to terminal STP. When the brake is applied, voltage is normally applied to terminal STP of the ECM through the STOP fuse and the stop light switch assembly, and the ECM turns the cruise control off.

DTC

DTC Detection Condition

Trouble Area

P0571

Voltage of STP signal and that of ST1- signal of ECM are less than 1 V for 0.5 seconds or more

  • Stop light switch assembly
  • Stop light switch circuit
  • ECM

WIRING DIAGRAM



CAUTION / NOTICE / HINT

HINT:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.

INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)

(a) Disconnect the stop light switch assembly connector.


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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A35-2 - Body ground

Always

11 to 14 V

Text in Illustration

*1

Front view of wire harness connector

(to Stop Light Switch Assembly)

(c) Reconnect the stop light switch assembly connector.


NG

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


OK

2.

INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)

(a) Disconnect the stop light switch assembly connector.


(b) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

A35-4 - Body ground

Ignition switch ON

11 to 14 V

Text in Illustration

*1

Front view of wire harness connector

(to Stop Light Switch Assembly)

(d) Reconnect the stop light switch assembly connector.


NG

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


OK

3.

INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Remove the stop light switch assembly (See page ).



(b) 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

3 - 4

Switch pin not pushed

10 kΩ or higher

1 - 2

Switch pin pushed

10 kΩ or higher

3 - 4

Switch pin pushed

Below 1 Ω

(c) Reinstall the stop light switch assembly (See page ).



NG

REPLACE STOP LIGHT SWITCH ASSEMBLY


OK

4.

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

(a) Disconnect the ECM connector.


(b) Disconnect the stop light switch assembly connector.

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

Standard Resistance (Check for Open):

For 1AR-FE

Tester Connection

Condition

Specified Condition

A49-29 (STP) - A35-1

Always

Below 1 Ω

A49-39 (ST1-) - A35-3

Always

Below 1 Ω

For 2GR-FE

Tester Connection

Condition

Specified Condition

A41-36 (STP) - A35-1

Always

Below 1 Ω

A41-35 (ST1-) - A35-3

Always

Below 1 Ω

Standard Resistance (Check for Short):

For 1AR-FE

Tester Connection

Condition

Specified Condition

A49-29 (STP) or A35-1 - Body ground

Always

10 kΩ or higher

A49-39 (ST1-) or A35-3 - Body ground

Always

10 kΩ or higher

For 2GR-FE

Tester Connection

Condition

Specified Condition

A41-36 (STP) or A35-1 - Body ground

Always

10 kΩ or higher

A41-35 (ST1-) or A35-3 - Body ground

Always

10 kΩ or higher

Text in Illustration

*1

Front view of wire harness connector

(to Stop Light Switch Assembly)

*2

Front view of wire harness connector

(to ECM)

*3

for 1AR-FE

*4

for 2GR-FE

(d) Reconnect the stop light switch assembly connector.

(e) Reconnect the ECM connector.

Result

Proceed to

NG

A

OK (for 1AR-FE)

B

OK (for 2GR-FE)

C


A

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


B

REPLACE ECM


C

REPLACE ECM

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