P0571

CRUISE CONTROL: CRUISE CONTROL SYSTEM: P0571: Stop Light Switch Circuit Malfunction

DTC P0571 - Stop Light Switch Circuit Malfunction

DESCRIPTION

While driving with cruise control, if the ECM detects that the brake pedal is depressed, the cruise control system will cancel. The stop light switch sends brake pedal status signals to the ECM.
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 ECM cancels cruise control operation.
The ECM 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.
At this time, the set speed is erased, the cruise control operation is canceled, and the power indicator blinks until the main switch is pushed OFF. Cruise control operation is prohibited until the main switch is pushed ON again.






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.

Cruise Control





OK:
OK: Display changes according to brake pedal operation described in above table.
OK -- REPLACE ECM
NG -- Continue to next step.
2. INSPECT STOP LIGHT SWITCH ASSEMBLY




(a) Disconnect the stop light switch connector.
(b) Measure the resistance of the switch.
Standard voltage:






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




(a) Disconnect the E5 and E6 ECM connectors.
(b) Turn the ignition switch ON.
(c) Measure the voltage of the wire harness side connectors.
Standard voltage:






Result





C -- REPAIR OR REPLACE HARNESS OR CONNECTOR
A -- REPLACE ECM
B -- Continue to next step.
4. INSPECT FUSE (STOP)
(a) Remove the STOP fuse from the driver side junction block ECU.
(b) Measure the resistance of the fuse.
Standard resistance:
Below 1 Ohms
NG -- REPLACE FUSE
OK -- Continue to next step.
5. CHECK WIRE HARNESS (MAIN BODY ECU - BATTERY)
(a) Disconnect the D2 ECU 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.
6. CHECK MAIN BODY ECU (for Driver Side)
(a) Reconnect the D2 ECU connector.
(b) Measure the voltage according to the value(s) in the table below.





Standard voltage:






NG -- REPLACE MAIN BODY ECU (for Driver Side)
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (MAIN BODY ECU - ECM)