Brake Lamp: Description and Operation

Current is applied at all times through a STOP fuse to TERMINAL 2 of the stop light SW.
When the Ignition SW is turned ON, current flows from the GAUGE fuse to TERMINAL 2 of the light failure sensor, and also flows through the rear light warning light to TERMINAL 3 of the light failure sensor.

STOP LIGHT DISCONNECTION WARNING
When the Ignition SW is turned ON and the Brake Pedal is pressed (Stop Light SW ON), if the Stop Light circuit is open, the current flowing from TERMINAL 7 of the light failure sensor to TERMINAL 1 changes, so the light failure sensor detects the disconnection and the warning circuit of the light failure sensor is activated.
As a result. the current flows from TERMINAL 3 of the light failure sensor --> TERMINAL 9 --> GROUND and turns the rear light warning light ON. By pressing the Brake Pedal, the current flowing to TERMINAL 2 of the light failure sensor keeps the warning circuit ON hold and the warning light ON until the Ignition SW is turned OFF.