Brake switch connected to brake pedal transfers brake operating state to PCM. For diagnosis of abnormal operation of Brake switch, two types of signals(one from Brake warning lamp switch, the other from Brake checking switch) are used and those two types output different signals at both condition, depressing or releasing brake pedal. When brake pedal is depressed brake checking switch outputs B+ voltage while brake warning lamp switch emits 0V. Conversly, when brake pedal is released, the output signals of each switch are opposite.
Checking input signals from brake lamp switch under detecting condition, if the operation state of brake lamp switch does not change for more than 3 sec., PCM sets P0571. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till cosecutive 2 driving cycle.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● PCM detects brake lamp input signal when vehicle stops. | ● Poor connection ● Open or short to ground in signal circuit ● Faulty PCM |
Enable Conditions | ● Engine works ● Vehicle speed signal is normal. ● Vehicle speed > 20 kph (during 1sec or more) | |
Threshold value | ● Vehicle speed < 3 kph ● Vehicle acceleration < -6 kph/s ● Brake lamp "OFF" and not changing of brake lamp signal for more 3 sec. | |
Diagnosis Time | ● Continuous | |
MIL On Condition | ● 2 driving cycles |
