How can I get started on fixing this?

  • 2007 CTS low beam headlight dot work highbeam do
    – JamesC442
    Aug 15, 2016 at 13:24
  • 1
    Can you clarify exactly what you're talking about? It's not making sense. Also, what trouble shooting have you done to try and fix your issue? Have you replaced bulbs? Tested/replaced relays? Tested/replace fuses? Tested the high beam mechanism? Aug 15, 2016 at 13:59
  • It is fine to post a minimal (e.g., the best you can figure out at the moment) question to get started, but when you do it really helps if you can get back to the question to respond to comments. People here are friendly and helpful and you'll probably find a comment asking for clarification (or an answer) within an hour or two.
    – dlu
    Aug 15, 2016 at 22:55

2 Answers 2


Here is an image of a dual-beam bulb. Note that it has 2 filaments as labelled:

enter image description here

You need to check if one of the filaments has fried. If the filament isokay for both high and low beam then you will need to replace your relay

Here is image of the fuse/relay block under the hood: enter image description here

Check for the low beam as highlighted below: enter image description here

  1. Test the relay (https://www.youtube.com/watch?v=ire7vyDqelg)
  2. Order the relay if not good
  3. Replace the relay

It is common for low beams to get used more than the highs, so it might be as simple as checking and changing the bulbs. Failing that, start by checking the fuse(es). If neither of those moves solve the problem, here are a few questions and answers that will probably help if you get it sorted out:

Also, take a look at the Related links on the right, there is often good information there.

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