Headlights went out on the way to work. I realized it is only low beam. High beam works fine, I can't find the fuse to replace it? Also replaced spark plugs because of car missing. I've replaced a coil pack last year for the same symptoms but it also stated coil pack in diagnosis test. After replacement of plugs the diagnostic tests reads misfire. My buddy said it will straighten it's self out but vehicle running worse now than before. Any suggestions? Gas consumption is extreme to say the least and don't put a lot of miles on the trailblazer daily and these same issues happened with the coil pack, including loss of power. Also various electrical problems seems to happen. Could this be a larger fuse that I'm not aware of that connects the different lights? When I run the AC the miss is worse because of the compressor but the issue still remains. Vehicle struggles sometimes to gain speed and gas petal will be to the floor, other times its as it should be. Plug change didn't seem to help except gas smell is gone. I'm not a mechanic but I can handle a few issues so please word things I'll understand, thanks in advance. Just want my vehicle back and running correctly.

  • 2
    It looks like there's a lot of different questions in here. Can you perhaps split this up into separate, clearer posts?
    – Jason C
    Aug 14 '16 at 1:28
  • Also, reading your title I realise your question is 2005 Chevy trailblazer 4dr 6cyl 4.2vortex... Not the most descriptive.
    – Hennes
    Aug 14 '16 at 12:03

Here is a diagram of the headlight circuits, you should be able to find the cause using this. Headlamp Fuses are in the engine compartment fuse block. I suspect Fuse 53, since this will stop both low beams from working, or a bad HDM relay or Headlamp switch., worst case it is an issue with the Body Control Module.

Click images to enlarge.

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Here is the headlight switch diagram if you should need it.

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  • Thanks for the diagram, I'm sure this will fix most of the electrical issues. The other symptoms you asked to be separated are a miss, same you would experience with a bad plug, loss of power at times idles hard when stopped. Changed plugs and boots yesterday but issues remain. Diagnostic didn't read coil pack as it did last year with these symptoms, it only states misfire. Aug 14 '16 at 1:56
  • Bad coil packs don't always trip a code.
    – Moab
    Aug 14 '16 at 19:57

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