Headlamp Control Module: Description and Operation

The Automatic Headlamps/Delayed Edit (AUTOLAMP) circuit controls the operation of lamps normally controlled by the Main Light Switch. The circuit has two basic functions: Automatic Lamps and Delayed Exit lamps.

Automatic Lamps

The Automatic Lamps circuit turns on the Headlamps, Exterior Lamps and Instrument Illumination Lamps when the Ignition Switch is in RUN, the Main Light Switch is in OFF, the system is turned ON and the ambient light level falls below a predetermined level, such as sunset. Also, the lamps will turn OFF when the ambient light level increases to a predetermined level.

Light Sensor/Amplifier

A Light Sensor/Amplifier, mounted under a group of perforated holes in the upper instrument panel pad, is exposed to ambient light. As the light level decreases, the Light Sensor's resistance increases. When resistance increases to a preset amount, the Amplifier applies power to the Autolamp Dual Coil Relay. The Headlamps, Exterior Lamps and Instrument Illumination Lamps turn ON. The lamps will remain ON until the system is turned OFF or the ambient light level increases. Turning the Ignition Switch to OFF while the Autolamp system is operating activates the Delayed Exit part of the circuit.

Delayed Exit

The Delayed Exit system keeps the lamps operated by the Autolamp system ON for a preselected period of time after the Ignition Switch is turned to OFF. The Delayed Exit system is turned ON by the same switch that controls the Automatic Lamp Switch system.

When the Ignition Switch is turned OFF while the Light Sensor/Amplifier and Autolamp Dual Coil Relay are operating the Headlamps, Exterior Lamps and Instrument Illumination Lamps, the Light Sensor/Amplifier continues to energize the Autolamp Dual Coil Relay and all lamps stay on. The Light Sensor/Amplifier will keep the Relay energized for a period of time ranging from a few seconds to 4-1/2 minutes, depending on the setting selected by the driver. The driver selects the Delayed Exit time period by rotating the Autolamp dial located behind the Main Light Switch knob. Turning the dial clockwise increases the period of the time that the lamps will stay ON.


NOTE: If it is necessary to have the lamps turn ON earlier or later than the factory setting, the Light Sensor can be adjusted. After gaining access to the Light Sensor/Amplifier, rotate the TURN ON ADJUSTMENT screw toward EARLIER or LATER, noting the manufacturer's directions which are printed on the unit.