Headlamp: Description and Operation

HEADLAMPS
All models are equipped with composite headlamps. Each composite headlamp consists of 1 halogen bulb, providing both high and low-beam operation, and a headlamp assembly. The bulb is separate from the assembly. The headlamp assembly does not need to be removed from the vehicle in order to replace the bulb. It is not necessary to re-aim the headlamps when replacing only the bulb.

The turn signal/headlamp switch lever is located on the left side of the steering column. The switch lever controls both the low-beam and high-beam headlamp operations. The lever is only serviceable as part of the combination switch. For combination switch removal and installation procedures, refer to Inflatable Restraint Steering Wheel Module Coil Replacement in Restraint Systems. A twist type knob on the end of the switch lever controls the operation of the parking lamps and the headlamps. A solid tone will sound as a reminder if you open the drivers door with the key out of the ignition and the park lamps or the headlamps on. When either the parking lamps or headlamps are activated, the following also illuminate:
- The tail lamps
- The side marker lamps
- The rear license plate lamps
- The instrument cluster assembly lamps
- The heater control unit lamp
- The radio lamp
- The cigar lighter lamp
- The IP ashtray lamp
- The manual selector lever lamp

The TAIL fuse applies voltage to the coil and the contacts in the tail lamp relay at all times. With the turn signal/headlamp switch lever in the park lamp or headlamp position, the coil is provided a ground through the turn signal/headlamp switch to G200. When the ambient light sensor senses a low light condition, a path to ground is provided to the coil through the sensor to G200. When the coil energizes, the contacts in the tail relay close and voltage is applied to the lamps mentioned above. All of the lamps illuminate because the lamps are grounded permanently.

LOW BEAM SYSTEM OPERATION
The headlamps may be turned on two different ways. First, when the ignition switch is turned to the ON position, voltage is applied to the ambient light sensor through the DEF Fuse. The ambient light sensor permanently grounds to G200. When the ambient light sensor senses a low light condition, a path to ground is provided to the coil of the headlamp relay through the ambient light sensor. This same signal is also provided to the DRL control module and disables DRL operation. Voltage is provided from the H/L Fuses, through the DRL diode to the coil of the headlamp relay. The relay contacts close providing a ground to the headlamps. The headlamps illuminate at full intensity. Second, when the end of the of the turn signal/headlamp switch lever is turned to the second detent position, the headlamps illuminate.

The daytime running lamps (DRL) control module and the turn signal/headlamp switch control the headlamps. The H/L, L and H/L, R Fuses supply voltage to the headlamps, the high beam indicator and the headlamp relay through the DRL diode at all times. With the switch in the HEAD position and the dimmer switch in low, ground is provided to the low beam filaments through the dimmer switch and the closed contacts of the Headlamp Relay to G200. The low beam filaments illuminate when the ground is supplied.

HIGH BEAM SYSTEM OPERATION
The high-beam headlamp operation is controlled using the turn signal/headlamp switch lever on the steering column. In order to change headlamp operation from low-beam to high-beam, push the switch lever toward the instrument panel until the detent is felt and release. With the switch lever in the high position, the high beam filaments in the headlamps ground through the dimmer switch, through the closed contacts of the headlamp relay to G200. The high beam filaments will light when the ground is supplied. The high-beam indicator-blue in the instrument cluster will light during high-beam headlamp operation. The ground path for the high beam indicator is the same as the high beam filaments. In order to change headlamp operation back to low-beam operation, pull the turn signal switch lever toward the driver until the detent is felt and release.