Twilight Sentinel

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

When the ignition switch is on and the head/park lamp switch is off, the system turns on the headlamps when road illumination becomes necessary. As daylight increases in the morning and illumination is no longer needed, it turns them off.

The system consists of a light sensitive photocell sensor, a lamp control module and a time delay control with a momentary 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 its light sensitive surface face up, in the I/P defroster grille, exposing it to the skylight through the windshield. The lamp control. module is mounted behind the I/P.

A time delay circuit in the lamp control module reduces the probability of the headlamps switching on or off while the vehicle is passing under viaducts, trees, bright lights, etc. This time is normally 23 seconds, and 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. This time delay can be adjusted from a few seconds to 3 minutes.

The twilight sentinel switch cannot be turned off permanently. If moved to the OFF position, it will automatically return to the ON position when released. While in PARK with the ignition in RUN, the headlamps can be cycled OFF if they have turned on automatically by moving the switch to OFF and releasing. The headlamps will return to automatic operation when the vehicle is shifted out of PARK.

If the head/park lamp switch is in the on position, the headlamps remain on after the ignition is turned off, regardless of the twilight sentinel control setting. However, a warning chime sounds when the driver's door is opened as a reminder to turn off the head/park lamp switch.