P0571

CRUISE CONTROL SYSTEM: P0571: Stop Light Switch Circuit Malfunction

DTC P0571 - Stop Light Switch Circuit Malfunction

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 cruise control.
Fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit.
The cancel condition occurs when positive battery voltage is applied to terminal STP.
When the brake is applied, battery positive 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 cruise control off.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT STOP LIGHT SWITCH ASSEMBLY





(a) Disconnect the stop light switch assembly connector.
(b) Measure the resistance according to the values in the table below.
Resistance:





NG -- REPLACE STOP LIGHT SWITCH ASSEMBLY
OK -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR





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





NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.
3. INSPECT ECM





(a) Reconnect the stop light switch connector.
(b) Disconnect the connector from the ECM.
(c) Turn the ignition switch to the ON position.
(d) Measure the voltage according to the value(s) in the table below.
Voltage:





NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPLACE ECM