Headlamp: Description and Operation

GENERAL DESCRIPTION

Exterior Headlamp Control
The headlamps and parklamps are illuminated via external relays which are controlled by the body controller module (BCM). When the parklamp switch is closed to ground the BCM grounds the parklamp relay coil which provides the power to the parklamps. This same parklamp power feed is also wired back into the BCM to provide the power feed for the PWM circuit. When the headlamp switch is closed to ground the BCM grounds both the low beam and high beam headlamp relays. The position of the hi-beam select switch will determine the mode of operation. Note: On Chrysler vehicle line when the high beams are selected both high beams and low beams will be illuminated. Dodge and Plymouth vehicle lines support only one mode of operation at a time.

Auto Headlamps
On vehicles equipped with the auto headlamp feature, the BCM will control the exterior lamp operation by monitoring the mode selection switch located in the headlamp control panel. When auto headlamp mode is selected the BCM will then monitor for a on/off signal from the Electro-Chromic Rear View mirror. The mirror will determine the appropriate ambient light levels for turning on/off the exterior lamps. If in auto headlamp mode, exterior lamps are on (due to darkness), and the ignition switch is cycled off, the BCM will enter headlamp delay mode (see Headlamp Delay Feature description).

Headlamp Time Delay
The headlamp Delay feature keeps the Headlamps on for 60 seconds giving the driver and passengers security lighting when exiting the vehicle. This feature is only available on vehicles equipped with RKE. The Headlamp Delay feature is activated by sequentially turning off the ignition, then both the headlamps and parklamps. The headlamps and parklamps must be turned off within 45 seconds of ignition transition to off to activate the headlamp delay. This 45 second window is new for the NS body Once the headlamp delay has been activated the headlamps will remain on for 60 seconds or until a parklamp, headlamp, auto headlamp or the ignition switch changes states.

DAYTIME RUNNING LAMPS

Junction Block Terminal Pins:

The Combination Flasher/DRL is a module providing turn signal, hazard warning, and daytime running light functions (for Canadian vehicles), and has been designed with internal relays to take advantage of low current switching requirements in the vehicle. It is plugged into the junction block at positions three and four, where all wiring associated with its operation is terminated. The junction block is adjacent to and left of the steering column of the vehicle. For diagnostic information refer to Turn Signal and Flashers.

On vehicles built for use in the United States, only position four is used. Vehicles built for use in Canada utilize both positions three and four. To gain access to the device, remove the lower steering column cover and knee blocker. Refer to Instrument Panel and Gauges.

System Function
The Combination Flasher/DRL may be operated in its hazard warning mode either with or without the ignition circuit being active. However, in order to operate in the turn signal mode or the DRL mode, the ignition circuit must be completed to the module.

While the Combination Flasher portion is idle, there is no current drawn through the module. The device does not become active in the turn signal or hazard warning modes until a signal ground circuit is supplied to either of the turn signal inputs or the hazard warning input. With the ignition OFF, there is no current drawn through the module.

While the ignition is ON, the front turn signal filaments are illuminated steadily thus providing the DRL function. The DRL function may be inhibited by applying a signal ground input from either the park brake circuit or the headlamp relay activation circuit.