Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM100000000VII7
Model Year Start: 2016 Model: Sienna Prod Date Range: [12/2015 - 08/2016]
Title: CRUISE CONTROL: DYNAMIC RADAR CRUISE CONTROL SYSTEM: P0571; Stop Light Switch Circuit Malfunction; 2016 MY Sienna [12/2015 - 08/2016]

DTC

P0571

Stop Light Switch Circuit Malfunction

DESCRIPTION

The ECM receives the brake demand signal from the stop light switch assembly and transmits it to the brake actuator assembly (skid control ECU). The brake actuator assembly (skid control ECU) receives the signal from the ECM and operates the brake actuator.

DTC No.

DTC Detection Condition

Trouble Area

P0571

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
  • Stop light switch circuit
  • ECM
  • Harness or connector

This trouble code is output when the ECM detects the stop light control relay error signal from the skid control ECU for 0.2 seconds or more while the dynamic cruise control is in operation.
  • Stop light control relay
  • Stop light control relay circuit
  • Brake actuator assembly (skid control ECU)
  • Harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE

1.

CHECK STOP LIGHT OPERATION

(a) Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

OK

Condition

Illumination Condition

Brake pedal depressed

On

Brake pedal released

Off
NG

GO TO LIGHTING SYSTEM (EXT)

OK

2.

READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH1, STOP LIGHT SWITCH2, BRAKE CANCEL SWITCH)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Radar Cruise / Data List.

(e) Check the Data List for proper functioning of the stop light switch.

Radar Cruise

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Stop Light Switch 1

Stop light switch signal /

ON or OFF

OK: Brake pedal depressed

OFF: Brake pedal released

-

Stop Light Switch 2

Stop light switch signal /

ON or OFF

OK: Brake pedal depressed

OFF: Brake pedal released

-

Brake Cancel Switch

Brake cancel signal /

ON or OFF

OK: Brake pedal depressed

OFF: Brake pedal released

-

OK:

Display changes according to brake pedal operation described in the table.

NG

GO TO STEP 8

OK

3.

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU))

(a) Disconnect the A58 stop light switch assembly connector.

(b) Disconnect the A4 brake actuator assembly (skid control ECU) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A58-1 - A4-22 (STP2)

Always

Below 1 Ω

A58-1 or A4-22 (STP2) - Body ground

Always

10 kΩ or higher

(d) Reconnect the A4 brake actuator assembly (skid control ECU) connector.

(e) Reconnect the A58 stop light switch assembly connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

CHECK HARNESS AND CONNECTOR (STOP LP RELAY - BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU))

(a) Remove the STOP LP relay from the engine room relay block.

(b) Disconnect the A4 brake actuator assembly (skid control ECU) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Relay terminal 1 - A4-31 (STPO)

Always

Below 1 Ω

Relay terminal 4 - A4-22 (STP2)

Always

Below 1 Ω

Relay terminal 3 - A4-2 (STP)

Always

Below 1 Ω

Relay terminal 1 or A4-31 (STPO) - Body ground

Always

10 kΩ or higher

Relay terminal 4 or A4-22 (STP2) - Body ground

Always

10 kΩ or higher

Relay terminal 3 or A4-2 (STP) - Body ground

Always

10 kΩ or higher

(d) Reinstall the STOP LP relay to the engine room relay block.

(e) Reconnect the A4 brake actuator assembly (skid control ECU) connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

INSPECT STOP LP RELAY

(a) Remove the STOP LP relay from the engine room relay block.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3-4

Battery voltage not applied between terminals 1 and 2

Below 1 Ω

Battery voltage applied between terminals 1 and 2

10 kΩ or higher

3-5

Battery voltage not applied between terminals 1 and 2

10 kΩ or higher

Battery voltage applied between terminals 1 and 2

Below 1 Ω

(c) Reinstall the STOP LP relay to the engine room relay block.

NG

REPLACE STOP LP RELAY
OK

6.

REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)

(a) Replace the brake actuator assembly (skid control ECU) (See page 2016 - 2017 MY Sienna [12/2015 - 11/2017]; BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: BRAKE ACTUATOR: REMOVAL ).

NEXT

7.

CHECK FOR DTCS (DTC P0571)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Clear the DTCs.

(d) Perform the following to make sure that the DTC detection conditions are met.

HINT:

If the detection conditions are not met, the malfunction cannot be detected.

  • Drive the vehicle at a speed for which cruise control operation is possible.
  • Turn the dynamic radar cruise control system on using the cruise control main switch (ON-OFF button).
  • Push the cruise control main switch to -SET to activate the dynamic radar cruise control system.

(e) Enter the following menus: Powertrain / Radar Cruise / Trouble Codes.

(f) Check for DTCs.

Result

Result

Proceed to

DTCs are not output

A

DTC P0571 is output

B

(g) Turn the engine switch off.

A

END
B

REPLACE ECM

8.

CHECK HARNESS AND CONNECTOR (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

Switch Condition

Specified Condition

A58-2 - Body ground

Always

11 to 14 V

Text in Illustration

*a

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
OK

9.

INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Inspect the stop light switch assembly (See page 2016 - 2020 MY Sienna [12/2015 -        ]; LIGHTING (EXT): STOP LIGHT SWITCH: INSPECTION ).

NG

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK

10.

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

(a) Disconnect the A58 stop light switch assembly connector.

(b) Disconnect the A39 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A58-3 - A39-35 (ST1-)

Always

Below 1 Ω

A58-1 - A39-36 (STP)

Always

Below 1 Ω

A58-3 or A39-36 (ST1-) - Body ground

Always

10 kΩ or higher

A58-1 or A39-36 (STP) - Body ground

Always

10 kΩ or higher

(d) Reconnect the A58 stop light switch assembly connector.

(e) Reconnect the A39 ECM connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

11.

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND)

(a) Disconnect the A58 stop light switch assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A58-1 - Body ground

Always

10 kΩ or higher

A58-3 - Body ground

Always

10 kΩ or higher

(c) Reconnect the A58 stop light switch assembly connector.

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR