Headlights dim

2006 CHEVROLET TRAILBLAZER
58,000 MILES
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CHRISTINEFULLER
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Headlights dim at random times and now I've noticed at the same time the heater fan power decreases. I've had the vehicle jumped twice in the past three months before I purchased a new battery. Is this an electrical problem, or alternator, or a relay?
Dec 14, 2012 at 1:48 AM
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JACOBANDNICKOLAS
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It sounds like the alternator is going bad. When the lights dim, check the alt gauge to see if it is low. With the engine running, it should be producing around 14 volts. With the engine off, it will drop to around 12v.

Let me know what you find.
Dec 14, 2012 at 1:53 AM
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TIMBUCK
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The headlights will only come on bright, when you change the dimmer they go off, no dim lights. Thanks Tim
May 11, 2020 at 12:23 PM (Merged)
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QUESTIONS32
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I am currently experiencing this problem with my 2005 trailblazer and I was wondering if you ever found out what was causing the problem???

I've been to the dealership twice now and they still have no idea so I'd appreciated any information that could help us. thanks
May 11, 2020 at 12:23 PM (Merged)
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RGASTER
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While driving to work my dim headlights went out....the bright lights work fine and the fog lights work fine...just the dim are out
May 11, 2020 at 12:23 PM (Merged)
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HMAC300
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check items in pic under hood fuse box. if ok have multi function switch tested and scanned for codes for body module.
May 11, 2020 at 12:23 PM (Merged)