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.

The system consists of a light sensitive photocell, 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 is mounted with its light sensitive surface face up, in the defroster grille, exposing it to the skylight through the windshield. The lamp control module is mounted. behind the left hand side of the IP, 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 when road illumination becomes necessary. As daylight increases in the morning and illumination is no longer needed, it turns them off.

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 10-30 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 4 minutes.

Setting the twilight sentinel system control to OFF allows normal headlamps operation using the head/park lamp switch. If the head/park lamp switch is moved to on, 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.