I have a 2002 Buick lesabre. When I start the car the head lights come on and the Dash lights are Dimmed. If I push the Twilight Sentinal switch all the way down the head lights turn off and the dash lights get bright. As soon as I shift into reverse the dash lights go dim even with though the head lights off. I can barely read the radio shift position and the odometer in the daylight. I just spent $300 for a new head light cluster switch. It still does the same thing.

bim or DIM ? the dimmer switch ! Interior Lamps
The interior lamps consists of two groups, lamps that can not be dimmed and lamps that can be dimmed. This first group consists of lamps that may not be dimmed. This includes those lamps that may be manually turned on by placing the interior lamp switch to the DOME position, or by opening a door or a compartment:
• Door courtesy lamps
• Footwell courtesy lamps
• Instrument panel (I/P) compartment lamp
• Overhead console courtesy lamps
• Reading courtesy lamps
• Rear compartment courtesy lamp
• Roof rail courtesy lamps
• Sunshade vanity mirror lamps

Interior Lamps Dimming
This group of interior lighting includes lamps which may be dimmed. This group uses a combination of class 2 controlled illumination and incandescent lamps:
• Air temperature switch
• Cigar lighter lamp
• Door switches
• Driver information center (DIC) switch
• Headlamp switch
• Head-up display (HUD) switch
• Heated seat switches
• HVAC control assembly
• Instrument panel cluster (IPC)
• Memory function switch
• Radio
• Steering wheel controls
• Window switches
For the interior lighting to be dimmed the following conditions must be met:
• A low light level has been detected by the dash integration module (DIM)
• Headlamp switch is placed in to the PARK or HEAD position
• Ignition switch is placed in the ON position
Then all class 2 displays and all incandescent back lighting will be illuminated to the level set by the instrument panel (I/P) dimmer switch. When the I/P dimmer switch is moved from MIN to MAX, all class 2 displays and all incandescent back lighting respond from minimum intensity to maximum brightness.
The DIM supplies battery positive voltage to the coil side of the PRK LP relay in the rear fuse block.
When the I/P dimmer switch is moved from MIN to MAX, then the instrument panel module (IPM), W/CJ2, or climate control panel (CCP), W/C67, applies a message to the class 2 communication circuit to the DIM. The DIM then applies a ground to the park lamp relay control circuit. This energizes the PRK LAMP relay and allows battery positive voltage to be applied through the DIMR fuse to the DIM. The DIM then illuminates the following incandescent lamps through the incandescent dimming output circuit:
• Cigar lighter lamp
• DIC Switch
• Headlamp switch
• HUD switch
• HVAC control assembly
• IPC
• Radio
• Steering wheel controls
The DIM also applies a message to the following class 2 controlled illumination components:
• Drivers door module (DDM)
• HVAC control assembly
• IPC
• Radio
The DDM will then send a message through the simple bus interface (SBI) to the RH front door module (RFDM). The door modules will then illuminate the following components through the incandescent dimming output circuit:
• Air temperature switch
• Heated seat switches (W/KA1)
• Memory function switch (W/A45)
• Power door lock switches
• Power window switches
The ground for these components are provided from the DDM and RFDM.
The following components are grounded at G200:
• Headlamp switch
• HVAC control assembly
• IPC
• Radio
• Steering wheel controls
The following components are grounded at G201:
• Cigar lighter lamp
• DIC Switch
• HUD switch

Is the noise actually coming from the switch area or coming from under the dash area? Possible daytime running light /twilight sentinal modual shorted out causing your issue. Unplug this module and if the headlights go out,this will be your problem

I am thinking it is attached to the light switch.
Terry

Could be you need a replacement relay for the headlight switching

I do not see a separate twilight module in the diagrams. The sensor signal goes to the bcm. Suspect the bcm is running the lights. The sensor looks to be in the front left bumper.

Some cars have a delay to give person light to go up their walkway to the house.Check owners manual it might tell you how to reset it.

Look for other light controls, this sounds like sentinal lighting, which has what looks like a dimmer style control that sets this light off delay. the goal is to give light until you get in the house. the delay is adjustable.

its more than likely the twilight sentinal sensor which is in the dash and would cause this issue. it will be a little blue sensor about the size of a dime under the left hand or possible centre of the dash. happy holidays

There is a module called the headlamp control module its located under the front carpet area above the centre hump under the heater box area we had a few of these and the relays used to stick keeping the headlight on and would not turn out. Im not to sure about the year though..Its a shot if you unplug the connectors lights will go out..Im assuming you checked the twilight sentinal switch did not get readjusted ,and you turned the parking light switch off on the drivers door panel at the top just under the small window..a fast sounding reminder bell will let you know the switch is on..Im not trying to insult some peoples intelligence but some people who just bought a lesabre dont realize the switches are there because they have always have the automatic headlight operating...Hope this is helpfull good luck..

Replace the switch