P0571 When voltage of STP terminal and that of ST1- terminal on the hybrid vehicle control ECU are less than 1 V...

DESCRIPTION

When the brake pedal is depressed, the stop light switch sends a signal to the hybrid vehicle control ECU. When the hybrid vehicle control ECU receives this signal, it cancels the cruise control. 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 hybrid vehicle control ECU through the STOP SW fuse and the stop light switch, and the hybrid vehicle control ECU turns the cruise control off.

DTC No.	DTC Detection Condition	Trouble Area
P0571	When voltage of STP terminal and that of ST1- terminal on the hybrid vehicle control ECU are less than 1 V for 0.5 sec. or more	Stop light switch Stop light switch circuit Hybrid vehicle control ECU

WIRING DIAGRAM

INSPECTION PROCEDURE

1. READ VALUE OF INTELLIGENT TESTER

1. Connect the intelligent tester to the DLC3.

2. Turn the ignition switch on, and turn the intelligent tester main switch on.

3. Check the DATA LIST for proper functioning of the stop light switch.

   Hybrid Vehicle Control ECU (Cruise control): 

   Item	Measurement Item / Display (Range)	Normal Condition	Diagnostic Note
   STP LIGHT SW M	Stop light switch signal (Main CPU) / ON or OFF	ON: Brake pedal depressed OFF: Brake pedal released	-

   OK:

   When brake pedal operation is performed the results will be same as above.
   

OK	REPLACE HYBRID VEHICLE CONTROL ECU

NG

2. INSPECT STOP LIGHT SWITCH

1. Disconnect the stop light switch connector.

2. 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

NG	REPLACE STOP LIGHT SWITCH

OK

3. CHECK WIRE HARNESS (STOP LIGHT SWITCH - BATTERY)

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

   Standard voltage:

   Tester Connection	Condition	Specified Condition
   S13-2 - Body ground	Always	10 to 14 V
   S13-3 - Body ground	Engine switch on (IG)	10 to 14 V

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4. CHECK HYBRID VEHICLE CONTROL ECU

1. Reconnect the stop light switch connector.

2. Disconnect the H29 connector from the hybrid vehicle control ECU.

3. Turn the ignition switch on.

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

   Standard voltage:

   Tester Connection	Brake Pedal Condition	Condition
   H29-31 (STP) - Body ground	Depressed	10 to 14 V
   H29-31 (STP) - Body ground	Released	Below 1 V
   H29-25 (ST1-) - Body ground	Depressed	Below 1 V
   H29-25 (ST1-) - Body ground	Released	10 to 14 V

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - HYBRID VEHICLE CONTROL ECU)

OK
REPLACE HYBRID VEHICLE CONTROL ECU