P0571

CRUISE CONTROL SYSTEM: P0571/52: Stop Light Switch Circuit

DTC P0571/52 - Stop Light Switch Circuit

DESCRIPTION

The cruise control system cancels cruising when the ECM detects that the brake pedal is depressed while cruise control driving. The stop light switch assembly sends signals to the ECM according to the brake pedal conditions. When the brake pedal is free, terminal ST1- is the positive (+) battery voltage, and terminal STP voltage is below 1 V. While depressing the brake pedal, terminal ST1- is below 1 V, and STP is positive (+) battery voltage. Under braking, the ECM cancels cruise control drive as one of the manual cancel functions.
The ECM outputs this trouble code when voltage of terminals ST1- and STP are both below 1 V for 0.5 second or more at the same moment.
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. INSPECT STOP LIGHT SWITCH OPERATION (FOR STOP LIGHT)
(a) Check that the stop light comes on while depressing the brake pedal, and goes off when releasing the brake pedal.
OK:





NG -- INSPECT STOP LIGHT SWITCH CIRCUIT
OK -- Continue to next step.
2. INSPECT STOP LIGHT SWITCH OPERATION (FOR BACK-UP SIGNAL)





(a) Turn the ignition switch off.
(b) Disconnect the stop light switch connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:





NG -- REPLACE STOP LIGHT SWITCH
OK -- Continue to next step.
3. INSPECT ECM





(a) Reconnect the stop light switch connector.
(b) Disconnect the ECM connector.
(c) Turn the ignition switch to the ON position.
(d) Measure the voltage according to the value(s) in the table below.
Standard voltage:
3MZ-FE
2AZ-FE









(e) Measure the voltage according to the value(s) in the table below.
Standard voltage:
3MZ-FE
2AZ-FE









NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - ECM)
OK -- REPLACE ECM