I have a faulty headlight relay in my 2005 Buick Sentry. We bought the part but could not find the the box where it goes. Is it in the dash? How do we get to it?

Sounds like two separate problems. For the headlight, check the headlight relay in the underhood fuse box (may be more than one if you have DRL), but may also be the headlight switch. For the dash lights, there may be a dead spot on the brightness control. Rotate it a few time to see if that fixes the problem.

In the passenger compartment relay box under the dash just left of the steering column.

I guess you could say there is no fuse for the dash lights.
The dimmer control on the headlight switch actually goes thru the body computer and the dash lights get their power from there. The body computer has several fuses involved. The other interior lights not controlled by the dimmer get power from the park lamp relay.

you may have a faulty relay, power is eaten up by your lights causing others to loose power. change the relay.

You have the headlamp switch set on auto or are you turning them on manually ? Low beams work ? but not high beams ? High beam relay in the under hood fuse box .relay #34 .

check the fuse in fuse box for the headlights....

where is the location of the headlamp relay on a 2001 Buick century

Hi J_livezey,
Your fuse box is located behind the right side of the dash,to the right of the glove box.Here is a diagram to better expalin.If you need anything else,let me know. Thanks,Chuck.

SOUND LIKE THE DRL RELAY STUCK CLOSED. OR THE LIGHT SENSOR ON DASH COULD BE FAULTY.

http://www.carfusebox.com/suzuki-forenza-2005-under-dash-fuse-boxblock-circuit-breaker-diagram/