For 1990-2009 cars

The headlamps are controlled by the following components:

• | The daytime running lamps (DRL) control module

• | The light switch

• | The dimmer switch

When the light switch is in the HEAD position, the headlamps are ON.The following conditions occur:

#### Dimmer Switch LO

When the dimmer switch is in the LO position, the following components provide ground to the low beam filaments in the headlamps:

• | The dimmer switch

• | The light 2 relay's closed contacts to G201

Because the headlamp fuses supply voltage to the headlamps at all times, the low beam filaments will light.

#### Dimmer Switch HI

When the dimmer switch is in the HI position, the following components provide ground to the high beam filaments in the headlamps:

• | The junction block

• | The dimmer switch

• | The light 2 relay's closed contacts to G201

Because the headlamp fuses supply voltage to the headlamps at all times, the high beam filaments will light.

Ground to the high beam indicator is provided in the same manner of the high beam filaments. Because the left headlamp fuse supplies voltage to the high beam indicator at all times, the indicator will also light.

#### Dimmer Switch in PASS

When the dimmer switch is in the PASS position, the following components provide ground to the high beam filaments in the headlamps:

• | The junction block

• | The dimmer switch

• | Back through the junction block to G203

Because the headlamp fuses supply voltage to the headlamps at all times, the high beam filaments will light.

Ground to the high beam indicator is provided in the same manner of the high beam filaments. Because the left headlamp fuse supplies voltage to the high beam indicator at all times, the indicator will also light.

### Ignition Switch is ON

With the ignition switch in the ON position or in the START position, voltage is applied to the DRL control module through the IG-COIL fuse. The DRL control module is permanently grounded to G201.

For the daytime running lamps to work correctly, the following conditions must occur:

• | The parking brake is disengaged.

• | The DRL control module does not receive a ground signal from the generator. A ground signal from the generator indicates that the generator is not charging the battery.

• | The light switch is in the OFF position or in the PARK position.

When the parking brake is engaged, the park brake switch closes providing a ground to the DRL module. This disables the DRL operation.

When the generator is not running, a switch in the generator closes providing a ground to the DRL module. This disables the DRL operation.

When the light switch is in the HEAD position, a path to G201 is provided to the coil of the light 2 relay and to the DRL control module to G201. This disables the DRL operation.

When all of the listed conditions for the DRL operation occur, the DRL control module provides a ground for the low beam filaments in the headlamps through the DRL control module to G201. Because the headlamp fuses supply voltage to the headlamps at all times, the intensity of the low beam filaments is 80 percent.

The DRL control module also provides ground to the daytime running lamps indicator when the DRL is operating. Because the IG-COIL fuse applies voltage to the indicator, the indicator will light.