Cruise Control System

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

DTC P0571 - Brake Switch "A" Circuit

DESCRIPTION

While driving with the cruise control, if the hybrid vehicle control ECU detects that the brake pedal is depressed, the cruise control operation will be canceled. The stop light switch sends brake pedal status signals to the hybrid vehicle control ECU. When the brake pedal is not depressed, terminal ST1- is equal to the positive (+) battery voltage and terminal STP is below 1 V. When the brake pedal is depressed, the hybrid vehicle control ECU cancels cruise control operation. The hybrid vehicle control ECU outputs this DTC when the voltage of terminals ST1- and STP are both below 1 V for 0.5 seconds or more at the same time. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit.






WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH)
(a) Check the DATA LIST for proper functioning of the stop light switch.

Hybrid vehicle control ECU





OK:
When brake pedal operation is performed, the results will be same as above.
OK -- REPLACE HYBRID VEHICLE CONTROL ECU
NG -- Continue to next step.
2. INSPECT STOP LIGHT SWITCH





(a) Disconnect the A35 switch connector.
(b) Measure the resistance of the switch.
Standard resistance:






NG -- REPLACE STOP LIGHT SWITCH
OK -- Continue to next step.
3. CHECK WIRE HARNESS (STOP LIGHT SWITCH - BATTERY)





(a) Disconnect the A35 switch connector.
(b) Measure the voltage of the wire harness side connector.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK HYBRID VEHICLE CONTROL ECU (STP, ST1- VOLTAGE)





(a) Disconnect the A54 ECU connector.
(b) Turn the power switch ON (IG).
(c) Measure the voltage of the wire harness side connector.
Standard voltage:






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