Headlamp Leveling Motor - Operation - Export

OPERATION

With the push button of the headlamp leveling switch control, voltage is adjusted at the headlamp leveling switch (rheostat). This signals the headlamp leveling motors to adjust the vertical headlamp beam pattern accordingly. Headlamps must be ON, and ignition in the ON or RUN position, in order for the leveling system to function.

The controller board and logic circuitry of the headlamp leveling motor control motor operation based upon a voltage signal input received from the resistor multiplexed headlamp leveling switch in the Accessory Switch Bank Module (ASBM) on the instrument panel center stack. When the motor is energized it will extend or retract the motor push-rod through the integral screw-drive transmission. The ball on the end of the push-rod is snapped into a socket on the back of the reflector within the front lamp unit housing, which will cause the reflector to move as the push-rod is extended or retracted, changing the angle at which the light is projected from the headlamp low and high beam bulbs.

The headlamp leveling motors and switch have a path to ground at all times. The headlamp leveling components operate on battery voltage, but the system will only operate when the exterior lighting is turned ON.

Because of active electronic elements within the headlamp leveling motor, it cannot be tested using conventional diagnostic tools and procedures. If the headlamp leveling motor is believed to be ineffective, the hard wired headlamp leveling motor circuits and the leveling switch must be tested before considering motor replacement. Use a scan tool and the proper diagnostic information.