P0571

CRUISE CONTROL: CRUISE CONTROL SYSTEM: P0571: Brake Switch "A" Circuit

DTC P0571 - Brake Switch "A" Circuit

DESCRIPTION

When the brake pedal is depressed, the stop light switch sends a signal to the hybrid vehicle control ECU.
Receiving the signal, the hybrid vehicle control ECU cancels the cruise control. Even if there is a malfunction in the stop light signal circuit while the cruise control is operating, normal driving is maintained due to fail-safe function.
Cruise control is canceled when voltage is applied to terminal STP.
When the brake pedal is depressed, voltage is applied to terminal STP of the hybrid vehicle control ECU through the STOP fuse and the stop light switch, and the hybrid vehicle control ECU cancels the cruise control.
When the brake pedal is released, voltage is applied to terminal ST1- of the hybrid vehicle control ECU through the IGN fuse and the stop light switch, and the hybrid vehicle control ECU can operate the cruise control.
HINT: Inspect the fuses and relays before confirming the suspected areas which are shown in the table below.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT STOP LIGHT SWITCH OPERATION
(a) Check that the stop light turns on when the brake pedal is depressed, and goes off when the brake pedal is released.
OK:
The stop light turns on/turns off normally.
HINT: The stop light uses the circuit on the terminal STP side of the hybrid vehicle control ECU.

NG -- GO TO STOP LIGHT SWITCH CIRCUIT
OK -- Continue to next step.

2. INSPECT STOP LIGHT SWITCH ASSEMBLY




(a) Remove the stop light switch.
(b) Measure the resistance of the switch.
Standard Resistance:






NG -- REPLACE STOP LIGHT SWITCH ASSEMBLY
OK -- Continue to next step.

3. CHECK WIRE HARNESS (SWITCH - BATTERY)




(a) Disconnect the S16 switch connector.
(b) Measure the voltage of the wire harness side connector.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. CHECK HYBRID VEHICLE CONTROL ECU




(a) Reconnect the S16 switch connector.
(b) Disconnect the H15 ECU connector.
(c) Turn the power switch on (IG).
(d) Measure the voltage of the wire harness side connector.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE HYBRID VEHICLE CONTROL ECU