Circuit Description

The stoplight switch is a normally open switch. The switch receives a fused battery voltage and grounds through a pull-up resistor in the turn/hazard flasher module. With brake pedal not applied, the turn/hazard flasher module should detect a low signal voltage on stoplight switch circuit. The turn/hazard flasher module sends input state of switch to PCM via Class II serial data. PCM uses data to determine condition of switch. With brakes applied, PCM compares stoplight switch input to TCC and/or extended travel brake switch input. If a transition occurs on the TCC and/or extended travel brakes switches without a transition on the stoplight switch, DTC will set.