2002 Chevy Impala Headlights don't work

ok when push the lever forward the high beams don't stay on ? then that lever should be replaced cause that's ur dimmer switch to switch between high/low beam lights if the lever is bad can surge you headlight and blow the headlights, have you check headlight bulbs its rare but it has happened that both blow at the same time

In the late 1990s GM and most other car companies changed the configuration of headlight circuits. Now the headlight switch provides the ground circuit instead of power. So yes there is a relay between the main switch and the dimmer.
The headlights get power from left and right 15amp fuses, and the relay and main switch provides the ground circuit. Your owner's manual should tell you which relay in the box is for headlights.

see this steps and fix it use the VOM or DVOM. God bless you
The Cause: Most likely no voltage to the headlights because of a bad headlight relay, fuse, module, headlight switch, dimmer switch or wiring fault.
To figure out what's causing your problem, start by inspecting the main fuse for the headlight circuit. See your Owners Manual for the location of this fuse. It is often located in the power center in the engine compartment, but may also be in the fuse panel under the dash.
If the fuse has blown, replace it with a new fuse (same amp rating) and try again. If the fuse blows immediately, there is a short in the headlight circuit that will have to be found and repaired before the headlights will work. If the fuse does not blow and the headlights work, problem solved (for now). There may be in intermittent short or overload that caused the fuse to fail.
If the fuse if okay, use a volt meter or 12-volt test light to check for power at the fuse. Most headlight circuits are on (powered) all the time, so there should be voltage to the power side of the fuse. No power at the fuse would indicate a wiring fault possibly in the fuse block or in the wiring between the fuse block and the battery. You'll need a wiring diagram to trace the wiring circuit and find the fault.
If the fuse is okay and there is power, the next check would be to find the headlight relay or control module. If the system uses a relay, pull it out and shake it. If anything inside rattles, replace the relay. Or buy another relay and plug that in to see if that restores power to the headlights.
On systems that use a module control module or daytime running lamps, about all you can do is eliminate other possibilities such as wiring faults, a bad relay or headlight switch first. If the module is getting power when the headlight switch is turned on, but the headlights fail to come on, the problem is likely a bad module. The module may be located in the front area of the engine compartment (common on Fords), under the dash or elsewhere in the front of the vehicle. You will probably need to refer to the vehicle service literature to find the module's location.
If the headlight relay or module do not receive voltage when the headlight switch is turned on, a bad switch is your problem. Switches get a lot of wear and tear, so it's not unusual for a switch to wear out after many years of service. Replacing a headlight switch can be difficult depending on whether is it located in the instrument panel or on the steering column.
If your headlights work on low beam, but you have no high beam, or they work on high beam but there is no low beam, the most likely cause is a bad dimmer switch. The dimmer switch is integrated into the steering column mounted headlight switch on most vehicles, so if the dimmer is not working, you will have to replace the entire switch.
DO NOT attempt to replace a steering column mounted headlight switch without first disconnecting the battery and waiting at least 20 minutes for the capacitors in the airbag circuit to discharge. The steering wheel will have to come off to replace the switch. Crossing up the wrong wires in the steering column could set off the air bag and cause personal injury.
If a headlight switch looks like it will be difficult to replace, don't try to do it yourself. Take your car to a dealer or repair shop and have them replace the switch for you.

Vic, the adjuster is either a allen key, torx, or #2 philips type bolt found close to the bolt that is holding headlight in place on inner fender rail/flange. I believe on the Impala the only adjustment is up and down of the light beam. Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."
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as the lights worked when you held the switch in position , check/ replace the light switch

change your signal light switch. i just had the same problem. cost me a 150.00 for an after market switch, comes with a full harness that plugs in under the dash.

if you have auto lights it could be the photo eye or its the headlight switch

Check headlight and high beam switch for power in, power out. If power there, change whichever switch isn't working (remember dimmer switch gets power from headlamp switch) If no power going to headlamp switch check main fuses and fusable links for problems.

there's a button on the right side of the steering wheel that says serv push that button. It's put right there for when they use them as police cars you can cut the headlights off. You will probably notice that dash lights are on.

I have an 2004 impala and every now and then it would lose the headlights for a couple of seconds and they would come back on. I finally replace the headlight switch and the problem went away. A switch, if I remember right, was about $500.