The brake light switch indicates brake pedal status to the ABS control unit. The switch is turned on when brake is depressed. The brake light switch is a normally-open contact which runs to battery voltage when active (brake depressed). When passive (brake not depressed), the cable is grounded via the break light bulbs.
The brake light signal is a reference to judge driver’s will for braking. ABS ECU monitor open circuit of brake light switch for normal ABS control.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Open circuit monitoring | ● Open circuit in brake switch line ● Faulty brake light switch ● Faulty input stage in HECU |
Detect Mode | ● Initial Check ● Outside the ABS control cycle ● Inside the ABS control cycle ● Diagnosis mode ● Failure mode | |
Enable Conditions | ● If both BLS(brake lamp switch) and BS(brake switch) have a same state for predetermined time, the failure is recognized. | |
Fail Safe | ● Inhibit the TCS/ESP control and allow the ABS/EBD control. ● The TCS/ESP warning lamps are activated. |
