Twilight Sentinel

The twilight sentinel is a feature which provides for the automatic ON-OFF control of the headlamps in response to the level of ambient light. The twilight sentinel also keeps the lamps ON for a preselected time period after the ignition is turned to the OFF position. The headlamps turn OFF automatically after the preselected time period elapses.

The system consists of a light sensitive photocell sensor, a lamp control module, and a time delay control with an ON/OFF switch. The automatic twilight sentinel circuit parallels the regular head/park lamp switch such that the head/park lamp switch must be OFF for automatic control.

The photocell sensor is mounted with the light sensitive surface face up, in the instrument panel defroster grille, exposing the photocell to the skylight through the windshield. The lamp control module is mounted behind the left hand side of the instrument panel, next to the steering column.

When the ignition switch is on, the head/park lamp switch is off, and the twilight sentinel control is on (any position except at OFF), the system turns on the headlamps whenever road illumination becomes necessary. As daylight increases in the morning and illumination is no longer needed, the system turns the headlamps off.

A time delay circuit in the lamp control module reduces the probability of the headlamps switching on or off while the vehicle passes under items such as viaducts, trees, bright lights, etc. This time is normally 10-30 seconds. The time cannot be adjusted. The variable twilight sentinel control adjusts only the time delay period during which the headlamps remain on after the ignition is turned off. The time delay may be adjusted from a few seconds to 4 minutes.

Setting the twilight sentinel system control to the OFF position allows normal headlamp operation using the head/park lamp switch. If the head/park lamp switch is moved to the ON position, the headlamps remain ON after the ignition is turned OFF, regardless of the setting on the twilight sentinel control. A warning chime sounds when the anyone opens the driver-side door. This chime is a reminder to turn oft the head/park lamp switch.