1.Stop lights and Hi-mounted stop light open circuit
When the stop lights and hi-mounted stop light are operating normally, the voltage of comparators 1 and 2 on the positive side when the lights are on is lower than the standard voltage input into the negative side. Therefore, comparators 1 and 2 output “0”.
Because of this, Tr remains in an off state and the rear light warning light goes out. From this state, if even one light circuit becomes open, the voltage of the comparator’s positive side raises and becomes greater than the standard voltage input into the negative side.
Therefore, comparators 1 or 2 output “1” to OR gate OR1.
Due to this, OR1 outputs “1” to a delay/holding circuit. The delay/holding circuit turns Tr on after 0.3 to 0.5 seconds. This turns on the rear light warning light on the combination meter.
The holding circuit operates until the ignition switch is turned off. Therefore, the warning light remains on.
2.Taillights open circuit
Like the stop light circuit, when the taillight circuit becomes open, comparator 3 judges that voltage has changed and outputs “1” to OR2. A signal is transmitted from OR2 to the delay/holding circuit to Tr and the rear light warning light comes on.