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Regular headlight issues

When I started my car, both my headlights were out, but then the drivers side came on for just a minute and then went out again. My brights do still work. Is this an electrical problem? If so, where might the problem lie?

I’d check the voltages directly at the bulbs. That will determine if you have bad bulbs or a wiring problem. If you don’t have 12 volts at the bulb, you need a wiring diagram and work your way back from there.

But a quick test is to check the connections for the bulbs for corrosion. That is, check the actual bulb contacts, and also any connector that plugs into the headlight assembly.

What year is this Impala?


Your post is the definition of “electrical problem”. Yes, you have an electrical problem.

Are your daytime running lights (DRLs) on? You know, the ones that light when you start the car but don’t turn on the headlights. No? Turn on the headlights, still no low beams? No? Probably needs new bulbs.

Both headlight bulb low beams may have burned out. It is likely that one burned out and you didn’t notice until the other went out. Since the high beams are on a different bulb or just a different filament in a single bulb, they usually still work. Have new bulbs installed and see if that fixes the problem. Bulbs are about $5 each for low beam bulbs.

If the DRLs turn on but the low beams go off when you turn on the headlights, you’ve got an electrical problem that needs to be tracked down by a mechanic.

Yes. May be a corroded connection somewhere in the wiring harness, faulty headlight relay, faulty bulbs, faulty fuse, ground problem, hard to say. A shop would usually start at the headlight fixtures, make some measurements there, and work back toward the battery to figure out where the problem is.

One night I went to drive my '75 Civic and both low beams were out.
Naturally I assumed both bulbs couldn’t go at the same time, so I checked the fuse,
then dreaded having to replace the switch.
Then I checked the bulbs with an ohmmeter, and indeed both bulbs were bad.
My guess was the filaments were thin and broke during the day when going over one of the many rough roads in Wash. DC.
More recently both oven bulbs wouldn’t light in my dual oven stove.
Again, assuming both bulbs wouldn’t go at the same time, I first removed the front panel and checked the switch, checked for voltage.
Again, it was both bulbs.
I’ll never learn.

I’ve had bulbs going from working to not working then back to working again. Eventually they stop working altogether, but bulbs can get into the Heisenberg Cat thing for a while anyway.

That would be Schrödinger’s cat…


That would be my first guess, and it’s very, very common for this to happen.
Re: the driver’s side coming on for just a moment, it’s rare, but I have seen an incandescent bulb fail such that under a bump or vibration the ends of the blown filament touch one another for just a moment and the bulb lights.

IMHO it’s always wise to first try new bulbs. That solves the problem the overwhelming majority of the time.

When I was fixing B52 bombers, it was emphasized to us to always check the breakers first (the circuit breakers relevant to the complaint). More than once I’ve been called to a fully armed aircraft at the end of the runway for a problem and solved it by resetting the breaker. Granted, the vibration in a B52 bomber sitting on the taxiway with eight jet engines operating is… shall we say… far, far greater in its vibration than in a car, but the principle is the same. Check the simple stuff first.

Heisenberg, Schrodinger … it’s all the same … lol …

Anybody here remember that old Cheech and Chong bit? From Santa Clause & His Old Lady …

Cheech Marin: Yeah, it really was, man. And then, man, he went down south, man, and they tried to cut of his hair and his beard, man. And all the time, he was getting stopped and pulled over and asked for his ID, man…just everywhere he went, he ran into too much recession, man.

Tommy Chong: No, man, you mean he ran into too much REPRESSION, man.

Cheech Marin: Aw, “repression”…“recession”…it’s all da same thing, man.

Hey, an MIT link. What a Car Talk coincidence! … lol …