Concealed Headlights

Concealed headlights enhance the vehicle's styling and aerodynamics

FIGURE. Concealed headlights enhance the vehicle’s styling and aerodynamics.

A vehicle equipped with a concealed headlight system hides the lamps behind doors when the headlights are turned off. When the headlight switch is turned to the HEADLIGHT position, the headlight doors open. Early systems used vacuum-controlled doors. Today most systems use electric motors.

Most limit switches operate off of a cam on the motor

FIGURE. Most limit switches operate off of a cam on the motor.

Electrically controlled systems can use either a torsion bar and a single motor to open both headlight doors, or a separate motor for each headlight door. Most systems will use limit switches to stop current flow when the doors are full up or full down. These switches generally operate from a cam on the reaction motor. Only one limit switch can be closed at a time. When the door is full up, the opening limit switch opens and the closing limit switch closes. When the door is full down, the closing limit switch is open and the opening limit switch closes. This prepares the reaction motor for the next time that the system is activated or deactivated.

An electrically controlled concealed headlight system with a manual control knob

FIGURE. An electrically controlled concealed headlight system with a manual control knob.

The electrically operated concealed headlight system provides a provision for manually opening the doors in the event of a system failure.

Pop-up headlight system wiring schematic

FIGURE. Pop-up headlight system wiring schematic.

Figure illustrates a system that incorporates an integrated chip (1С). Each motor has its own relay and limiting switches. When the limit switches are in the A-B position, the doors are full open. When the switches are in the A-C position, the doors are full closed.

Current flow with the headlight switch OFF and the headlight doors closed

FIGURE. Current flow with the headlight switch OFF and the headlight doors closed.

Figure illustrates another method used to operate the electric motors of a concealed headlight system. When the ignition switch is in the RUN position but the headlight switch is off, current flows through the ignition switch to the relay. The relay is energized because the coil is grounded through the headlight filaments. With the coil energized, the relay points close. However, the door closing limit switch is open. This results in a de-energized door closing field winding.

When the headlight switch is turned to the HEADLIGHT position, current continues to flow to the relay coil through the ignition switch. However, current is also sent to the other side of the relay coil from the headlight switch. Voltage is equal on both sides of the relay coil, so there is no voltage potential and the coil is de-energized. The relay contact points close to the door opening field winding. With the door opening limit switch closed, the motor operates until the limit switch is opened.