Lights all flicker. When I an in the cabin the head lights flicker. I want to test my fuses with a circuit tester.

Should the engine be running or will I be blown away?

Please help, I'm a newbie to car electronics.

thank you

  • 1
    You might try to use some more detail - it's hard to tell what you're asking. When do the lights flicker? What type of tester are you using?
    – JPhi1618
    Nov 30, 2015 at 15:21

1 Answer 1


I would test with a test light, not a circuit tester. A test light uses the car's battery, a circuit tester has its own battery and basically test for connectivity.

When you look at the fuses, one side will be input and the other side output. If the fuse is good, you will have voltage at both sides, if the fuse is blown, you will only have voltage at the input side.

connect the clip to ground (unpainted part of the body, bolt that goes through the body, dash frame, basically anything metal) and touch it to the sides of the fuse. On a 'push in' fuse, you can touch the terminals through the top of the fuse.

I do not believe the issue is a fuse. With fuses, they are either good and it works, or they blow and it does not work. The only thing fuse related that would cause flickering is if the fuse is loose.

I would look at grounds or your headlight switch.

  • thanks. it's an led circuit tester. no battery internal on it. I thought it might be ground. I how can I test ground? where are the ground wires?
    – e Barney
    Nov 30, 2015 at 20:42
  • i know that there's a ground from the battery to the heat shield or frame; but are there others? and where could they be? thank you.
    – e Barney
    Dec 1, 2015 at 0:31
  • Any place you find bare metal is a ground spot. If you are looking near the fuse panel, you will want to look for a bare bolt which is attached to the body. Dec 1, 2015 at 0:41
  • The grounds that would cause the headlights to flicker would be near the headlights or the headlight switch. Its vehicle specific. A schematic of the lighting system will be useful. I would jiggle the wires and see if you can find one that leads to the flickering.
    – rpmerf
    Dec 2, 2015 at 12:36

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