DYNAMIC RADAR CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DTC Code	DTC Name
P0571	Brake Switch "A" Circuit

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 dynamic radar cruise control. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. The cancellation condition 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 dynamic radar cruise control system off.
The ECM receives the brake demand signal from the driving support ECU assembly and transmits it to the skid control ECU (brake actuator assembly). The skid control ECU (brake actuator assembly) receives a signal from the ECM and operates the skid control ECU (brake actuator assembly). The skid control ECU (brake actuator assembly) operates the brake actuator assembly and at the same time illuminates the stop light by operating the stop light control ECU assembly*1 or STOP LP relay (stop light control relay)*2.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
P0571	Brake Switch "A" Circuit	When the ignition switch is turned ON and the dynamic radar cruise control system is operating, voltage of STP terminal and that of ST1- terminal of ECM are less than 1 V for approximately 0.5 seconds or more. While the dynamic radar cruise control system is operating (vehicle-to-vehicle distance control mode), the ECM detects the stop light control ECU assembly error signal from the skid control ECU (brake actuator assembly) for approximately 0.2 seconds or more1. While the dynamic radar cruise control system is operating (vehicle-to-vehicle distance control mode), the ECM detects the STOP LP Relay (stop light control relay) signal from the skid control ECU (brake actuator assembly) for approximately 0.2 seconds or more2.	Stop light switch assembly Stop light switch circuit ECM Stop light control ECU assembly1 STOP LP relay (stop light control relay)2 Stop light control ECU assembly circuit1 STOP LP relay(Stop light control relay) circuit2 Skid control ECU (brake actuator assembly) ECM

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

P0571

Brake Switch "A" Circuit

When the ignition switch is turned ON and the dynamic radar cruise control system is operating, voltage of STP terminal and that of ST1- terminal of ECM are less than 1 V for approximately 0.5 seconds or more.
While the dynamic radar cruise control system is operating (vehicle-to-vehicle distance control mode), the ECM detects the stop light control ECU assembly error signal from the skid control ECU (brake actuator assembly) for approximately 0.2 seconds or more*1.
While the dynamic radar cruise control system is operating (vehicle-to-vehicle distance control mode), the ECM detects the STOP LP Relay (stop light control relay) signal from the skid control ECU (brake actuator assembly) for approximately 0.2 seconds or more*2.

Stop light switch assembly
Stop light switch circuit
ECM

Stop light control ECU assembly*1
STOP LP relay (stop light control relay)*2
Stop light control ECU assembly circuit*1
STOP LP relay(Stop light control relay) circuit*2
Skid control ECU (brake actuator assembly)
ECM

*1: for LED Type Stop Light
*2: for Bulb Type Stop Light

WIRING DIAGRAM

for 2AR-FE
*a	from Battery
*b	STOP
*c	from IG2 Relay
*d	Stop Light Switch Assembly

for 3ZR-FAE, 3ZR-FE
*a	from Battery
*b	STOP
*c	from IG2 Relay
*d	Stop Light Switch Assembly

for 2AD-FHV, 2AD-FTV
*a	from Battery
*b	STOP
*c	from IG2 Relay
*d	Stop Light Switch Assembly

for 2WW
*a	from Battery
*b	STOP
*c	from IG2 Relay
*d	Stop Light Switch Assembly

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following procedure.
When replacing the skid control ECU (brake actuator assembly), perform zero point calibration.
When the entry start function does not operate, check the entry and start system (for start function)*.

*: w/ Entry and Start System

PROCEDURE

READ VALUE USING GTS (BRAKE CANSEL SWITCH)

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Radar Cruise1 / Data List.

Read the Data List according to the display on the GTS.

OK
Display changes according to brake pedaloperation described in above table.

for 2AD-FHV, 2AD-FTV:

Powertrain > Radar Cruise1 > Data List

Tester Display	Measurement Item	Range	Normal Condition	Inspection Item
Stop Light Switch 1	Stop light switch status	ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

Tester Display

Measurement Item

Range

Normal Condition

Inspection Item

Stop Light Switch 1

Stop light switch status

ON or OFF

ON: Brake pedal depressed

OFF: Brake pedal released

Powertrain > Radar Cruise1 > Data List

Tester Display
Stop Light Switch 1

for 2AR-FE, 3ZR-FE, 3ZR-FAE:

Powertrain > Radar Cruise1 > Data List

Tester Display	Measurement Item	Range	Normal Condition	Inspection Item
Brake Cancel Switch	Stop light switch status	ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

Tester Display

Measurement Item

Range

Normal Condition

Inspection Item

Brake Cancel Switch

Stop light switch status

ON or OFF

ON: Brake pedal depressed

OFF: Brake pedal released

Powertrain > Radar Cruise1 > Data List

Tester Display
Brake Cancel Switch

for 2WW:

Powertrain > Cruise Control > Data List

Tester Display	Measurement Item	Range	Normal Condition	Inspection Item
Brake Cancel Switch	Stop light switch status	ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

Tester Display

Measurement Item

Range

Normal Condition

Inspection Item

Brake Cancel Switch

Stop light switch status

ON or OFF

ON: Brake pedal depressed

OFF: Brake pedal released

Powertrain > Cruise Control > Data List

Tester Display
Brake Cancel Switch

Result

Proceed to
OK
NG

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

CHECK STOP LIGHT OPERATION

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

Condition	Illumination Condition
Brake pedal depressed	On
Brake pedal released	Off

Result

Result	Proceed to
OK (w/ Entry and Start System)	A
OK (w/o Entry and Start System)	B
NG	C

CHECK HARNESS AND CONNECTOR (STP2 TERMINAL VOLTAGE) Click here

GO TO LIGHTING SYSTEM Click here

CHECK HARNESS AND CONNECTOR (STPO TERMINAL VOLTAGE)

Turn the ignition switch off.
*a
Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

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

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A80-26 (STPO) - Body ground	Always	11 to 14 V

Result

Proceed to
OK
NG

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

PERFORM ACTIVE TEST USING GTS (STOP LIGHT RELAY)

Enter the following menus: Chassis / ABS/VSC/TRC / Active Test.

Perform "Active Test" according to the display on GTS.

Chassis > ABS/VSC/TRC > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Stop Light Relay	Stop lights	ON or OFF	Test possible at vehicle speed of 0 km/h (0 mph)

Chassis > ABS/VSC/TRC > Active Test

Tester Display
Stop Light Relay

Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

Check the stop light switch assembly operation using the Data List and stop light operation by performing an Active Test.

Chassis > ABS/VSC/TRC > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Stop Light Relay Output	Stop light control relay output	ON or OFF	ON: Relay output on (Stop light on) OFF: Relay output off (Stop light off)	-

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Stop Light Relay Output

Stop light control relay output

ON or OFF

ON: Relay output on (Stop light on)

OFF: Relay output off (Stop light off)

Chassis > ABS/VSC/TRC > Data List

Tester Display
Stop Light Relay

Result

Result	Proceed to
When Active Test performed, Data List item not changes between ON and OFF	A
When Active Test performed, Data List item changes between ON and OFF and stop lights turn on and off	B

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

INSPECT SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)

Enter the following menus: Chassis / ABS/VSC/TRC / Active Test.

Perform "Active Test" according to the display on GTS.

Chassis > ABS/VSC/TRC > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Stop Light Relay	Stop lights	ON or OFF	Test possible at vehicle speed of 0 km/h (0 mph)

Chassis > ABS/VSC/TRC > Active Test

Tester Display
Stop Light Relay

*a	Component with harness connected (Stop Light Switch Assembly)

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A77-4 (ACC) - Body ground	Active test is OFF	11 to 14 V
A77-4 (ACC) - Body ground	Active test is ON	Below 1.5 V

Result

Proceed to
OK
NG

REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) Click here

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

Disconnect the A80 skid control ECU (brake actuator assembly) connector.
Disconnect the A77 stop light switch assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A80-35 (STP) - A77-1 (OUT)	Always	Below 1 Ω
A80-35 (STP) or A77-1 (OUT) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

Disconnect the A80 skid control ECU (brake actuator assembly) connector.
Disconnect the A77 stop light switch assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A80-26 (STPO) - A77-4 (ACC)	Always	Below 1 Ω
A80-26 (STPO) or A77-4 (ACC) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK HARNESS AND CONNECTOR (STP2 TERMINAL VOLTAGE)

Turn the ignition switch off.
*a
Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

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

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

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
A80-5 (STP2) - Body ground	Stop light switch assembly on (Brake pedal depressed)	8.5 to 14 V
A80-5 (STP2) - Body ground	Stop light switch assembly off (Brake pedal released)	Below 1.5 V

Result

Proceed to
OK
NG

GO TO STEP 3 Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

Disconnect the stop light switch assembly connector.

*a	Front view of wire harness connector (to Stop Light Switch Assembly)

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A77-7 (B) - Body ground	Always	11 to 14 V
A77-6 (B) - Body ground	Ignition switch ON	11 to 14 V
A77-6 (B) - Body ground	Ignition switch off	Below 1 V

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

Disconnect the ECM connector.

*a	Front view of wire harness connector (to ECM)

for 2AR-FE:

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A62-24 (ST1-) - Body ground	Ignition switch ON, brake pedal depressed	Below 1.5 V
A62-24 (ST1-) - Body ground	Ignition switch ON, brake pedal released	7.5 to 14 V
A62-11 (STP) - Body ground	Brake pedal depressed	7.5 to 14 V
A62-11 (STP) - Body ground	Brake pedal released	Below 1.5 V

*a	Front view of wire harness connector (to ECM)

for 3ZR-FAE, 3ZR-FE:

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A62-10 (ST1-) - Body ground	Ignition switch ON, brake pedal depressed	Below 1.5 V
A62-10 (ST1-) - Body ground	Ignition switch ON, brake pedal released	7.5 to 14 V
A62-9 (STP) - Body ground	Brake pedal depressed	7.5 to 14 V
A62-9 (STP) - Body ground	Brake pedal released	Below 1.5 V

*a	Front view of wire harness connector (to ECM)

for 2AD-FHV, 2AD-FTV:

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A61-34 (ST1-) - Body ground	Ignition switch ON, brake pedal depressed	Below 1.5 V
A61-34 (ST1-) - Body ground	Ignition switch ON, brake pedal released	7.5 to 14 V
A61-35 (STP) - Body ground	Brake pedal depressed	7.5 to 14 V
A61-35 (STP) - Body ground	Brake pedal released	Below 1.5 V

*a	Front view of wire harness connector (to ECM)

for 2WW:

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

Standard Voltage

Tester Connection	Condition	Specified Condition
A62-10 (ST1-) - Body ground	Ignition switch ON, brake pedal depressed	Below 1.5 V
A62-10 (ST1-) - Body ground	Ignition switch ON, brake pedal released	7.5 to 14 V
A62-48 (STP) - Body ground	Brake pedal depressed	7.5 to 14 V
A62-48 (STP) - Body ground	Brake pedal released	Below 1.5 V

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK STOP LIGHT SWITCH ASSEMBLY

Temporarily replace the stop light switch assembly with a new or normally functioning one.

Click here
Clear the DTCs.

Click here
1. for 2AD-FHV, 2AD-FTV:
  
  Powertrain > Radar Cruise1 > Clear DTCs
2. for 2AR-FE, 3ZR-FE, 3ZR-FAE:
  
  Powertrain > Radar Cruise1 > Clear DTCs
3. for 2WW:
  
  Powertrain > Cruise Control > Clear DTCs

Check for DTCs.

Click here

for 2AD-FHV, 2AD-FTV:

Powertrain > Radar Cruise1 > Trouble Codes
for 2AR-FE, 3ZR-FE, 3ZR-FAE:

Powertrain > Radar Cruise1 > Trouble Codes
for 2WW:

Powertrain > Cruise Control > Trouble Codes

Result

Result	Proceed to
DTC is not output	A
DTC P0571 is output	B

END (STOP LIGHT SWITCH ASSEMBLY WAS DEFECTIVE)

REPLACE ECM for 2AD-FHV: Click here
REPLACE ECM for 2AD-FTV: Click here
REPLACE ECM for 2AR-FE: Click here
REPLACE ECM for 3ZR-FAE: Click here
REPLACE ECM for 3ZR-FE: Click here
REPLACE ECM for 2WW: Click here