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Greg A
Greg A, Master Troubleshooter
Category: Chevy
Satisfied Customers: 8736
Experience:  Working with Electronics & Cars for 25+ Years
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2004 Chevrolet Impala: all of the fuses and relays I..located under

Customer Question

Why won't the headlights work on my 2004 Chevrolet Impala. I have looked at all of the fuses and relays I can find. I have replaced the relay that is located under the dash and also replaced the switch on the dash. Any other ideas?? Thanks
Submitted: 8 years ago.
Category: Chevy
Expert:  Greg A replied 8 years ago.

Hello & Welcome,


Do you have a 12 volt test light or multimeter you can use to do some tests?


Also, are there any other lights that do not work?



Customer: replied 8 years ago.
Unfortunately I don't have any testing equipment. All other lights and electrical items function normally. When I start the car the parking lights turn on automatically. The daytime running lights eventually turn on when I drive the vehicle during the day. The high beams work fine.
Expert:  Greg A replied 8 years ago.

OK - Thanks,


So it sounds like the low beam headlights are the only lights that are not working.


Does the high beam indicator on the dash work properly (turns on & off when switching between low & high beams)?



Customer: replied 8 years ago.
Yes it does work fine.
Expert:  Greg A replied 8 years ago.

Thanks for that information.


It sounds like either you have an issue with the low beam lights themselves (they sometimes do go bad at the same time, or there is a problem with the headlight dimmer switch.


I would really like you to have a test light or multimeter to test this, but you could use a fused jumper wire (a fuse with wires attached) to do some testing. If you look at the schematics below, you will see where the dimmer is switched between the high and low beams. If you can use a fuse jumper wire to connect the Dark Blue wires at the back of the low beam bulbs to a good frame ground, then you could test if the bulbs are good. If the bulbs are good, the lights will come on when you make that connection.






Be careful to NOT touch the orange wires with the jumper, or you could blow a fuse.


I hope this helps. Please let me know what you find or if you have more questions.


Take Care, Greg A.



Customer: replied 8 years ago.
Thanks I have already replaced the bulbs for the low beams. Are you saying something else could go wrong with the lights or just that the bulbs could both burn out at the same time? I have had that happen before on other vehicles. So would that point me to just the dimmer switch?
Expert:  Greg A replied 8 years ago.

Yes, the bulbs could go out at the same time. It has happened to me too.


If the high beams are working, and the low beams are not, then the most likely component would be the dimmer switch. The schematic shows that the only difference between the low and high beam setting it that the ground side of the circuit is switched between the low and high beam bulbs.


Again, it would be nice to test first before replacing a part, but that is the most likely suspect.


Thanks, XXXXX



Greg A and 3 other Chevy Specialists are ready to help you
Customer: replied 8 years ago.
Thanks for your help!
Expert:  Greg A replied 8 years ago.

You are quite welcome,


Please let me know how it turns out.


Take Care, Greg A.

Customer: replied 8 years ago.
Thanks Greg for your recent help. I replaced the multifunction (Dimmer Switch) yesterday and everything works great. I was able to save a few hundred dollars doing this myself. Your answers were very helpful. Take Care.
Expert:  Greg A replied 8 years ago.

Hi again & thanks for letting me know.


I am glad I could save you some time & money on this project. Please let us know if you need any further help in the future.


Take Care, Greg A.