equipped vehicles is combined with the neutral
Figure 2-70.Turn signal flasher.
pedestrians, whenever the vehicle is shifted into
reverse. The backup light system has a fuse, gearshift-
or transmission-mounted switch, two backup lights,
and wiring to connect these components.
The backup light switch closes the light circuit
when the transmission is shifted into reverse. The most
common backup light switch configurations are as
The backup light switch mounted on the
transmission and operated by the shift lever.
The backup light switch mounted on the steering
column and operated by the gearshift linkage.
The transmission- or gearshift-mounted backup
light switch on many automatic transmission-
All vehicles that are used on public highways must
be equipped with a stoplight system. The stoplight
system consists of a fuse, brake light switch (fig. 2-71),
two rear warning lights, and related wiring.
The brake light switch on most automotive
equipment is mounted on the brake pedal. When the
brake pedal is pressed, it closes the switch and turns on
the rear brake lights. On construction and tactical
equipment, you may find a pressure light switch. This
type of switch uses either air or hydraulic pressure,
depending on the equipment. It is mounted on the
master cylinder of the hydraulic brake system or is
attached to the brake valve on an air brake system. As
the brakes are depressed, either air or hydraulic
pressure builds on a diaphragm inside the switch. The
diaphragm closes allowing electrical current to turn on
the rear brake lights.
EMERGENCY LIGHT SYSTEM
The emergency light system, also termed hazard
warning system, is designed to signal oncoming traffic
that a vehicle has stopped, stalled, or has pulled up to
the side of the road. The system consists of a switch,
flasher unit, four turn signal lights, and related wiring.
The switch is normally a push-pull switch and is
mounted on the steering column.
When the switch is closed, current flows through
the emergency flasher. Like a turn signal flasher, the
emergency flasher opens and closes the circuit to the
lights. This causes all four turn signals to flash.
Figure 2-71.Brake light switches.