Twilight Sentinel

Description
The twilight sentinel is an option which provides for automatic on-off control of the headlamps in response to the level of ambient light. It also keep 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 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 its light sensitive surface face up, in the I/P trim panel exposing it to the skylight through the windshield. The lamp control module is mounted behind the center of the I/P, above the HVAC case.

Operation
When (1) the ignition switch is on, (2) the head/park lamp switch is off, and (3) 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 four minutes.

Setting the twilight sentinel system control to "OFF" allows normal headlamps operation using the bead/park lamp switch. 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.