The Stop lamp switch is used to judge whether the acceleration system is abnormal or not. The stop lamp switch has a duplex system(signals brake test or brake light) to memorize the abnormality when the signals of depressing and releasing the brake pedal are detected simultaneously.
Checking input signals from stop lamp switch under detecting condition, if the operation state of stop lamp switch does not change for more than 3 sec., ECM sets P0571. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item
Detecting Condition
Possible cause
DTC Strategy
ECM detects stop lamp input signal when vehicle stops.
Poor connection
Open or short to ground in signal circuit
Faulty ECM
Enable Conditions
Engine works
Vehicle speed signal is normal.
Vehicle speed > 20kph (during 1sec or more)
Threshold value
Vehicle speed < 3kph
Vehicle acceleration < -6kph/s
Stop lamp "OFF" and not changing of stop lamp signal for more 3 sec.
Diagnosis Time
Continuous
MIL On Condition
NO MIL ON(DTC only)
Fig.1) Normal data of Brake Switch during brake pedal released after depressed.