Blinker blinks fast

When I turn on my left blinker it blinks real fast and the front blinker doesn’t work. I have changed the bulb and it still doesn’t work what is wrong?

I forget what that means and… Just looked it up, it’s supposed to mean a faulty bulb so you may have to change another one. and maybe even a side bulb that does not flash. Bulbfest: some kind of concert or a wild goose chase held during Bulbcheck; see above.

It means there’s a short to ground somewhere - causing excessive current to pass through the blinker relay - and hence the rapid blinking.

As pleasedodgevan2 noted, often it’s a faulty bulb, where the element has shorted to ground.
If new bulbs don’t cure it, you’ll need to look deeper - starting first at rusted out bulb sockets.

Usually, when the turn signals blink too quickly, a bulb is out. I would think that a short to ground would blow the fuse for the circuit.

@triedaq, the reason the fuse doesn’t blow is because the other working bulb(s) in the circuit limit the current.

The flasher unit is actually a self-resetting circuit breaker, so I suppose a short to ground might not blow the fuse. However, I would suspect bad contact in the socket or a broken wire. The OP might turn on the emergency flashers and see if what happens.

Before making this overly complicated, first thing to do is make sure all the bulbs that are supposed to blink, do blink. Compare the left to the right side, and check both the front and rear of the vehicle. If all the bulbs are blinking, the same on both sides of the car, but one side is blinking fast, and the other side normal, then you do have a more complicated problem.

The “fast blink” means that your car sees insufficient load on the turn signal unit. Generally, this means a bulb is out (unless you did something like replace the turn signals with LEDs.) It is designed to alert you to that fact.

You either have a bad bulb, the wrong bulb or a weak or no ground.

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The “fast blink” means that your car sees insufficient load on the turn signal unit.

Honest curious question. How would an insufficient load on the flasher cause “fast blink”?

@JoeMario…the bulb acts as a load on the spring steel inside the flasher. Since a bulb (load) is inoperative the spring steel cools more rapidly and snaps back to start the cycle in a more rapid manner hence…a faster blink.

@missleman
I don’t understand your reply.

If one of the turn signal bulb filaments is broken, then there will be an open circuit and no current will flow through the resistive wire in the flasher. The behavior will be no blinking at all.

If there’s a short somewhere, then there will be a higher than normal amount of current through the flasher’s resistive wire, causing the bimetallic strip to heat up and bend more quickly - and hence “open” more quickly.

If my understanding is incorrect, please clarify.

@JoeMario you are incorrect.

The two (or more) flashers are wired in parallel, not series. Losing one of the bulbs will NOT kill the other, like cut-rate Christmas lights. You’d still have the unaffected bulb/s working…this is an important safety consideration.

AFAIK, modern turn signals have “logic” built into them, such that, if an unusually low current us drawn, they blink fast to alert the driver. This would happen in the case of a burnt out bulb (or switching bulbs to LEDs, which draw less by design).

The reverse, a short JUST bad enough to P.O. the flasher unit, but not fry the fuse, is statistically improbable. Shorts that aren’t blatant usually manifest themselves by being intermittant, not a weak, constant leak.

@meanjoe75fan
Are you saying that increased current flow through the flasher unit won’t cause fast blinking?

Traditional mechanical flashers operate the way I describe. Increase the current through the flasher, and the bimetallic strip operation reacts more rapidly.

The OP didn’t state the year of his Impala, so it’s not clear what logic his unit has.

I don’t disagree, per se; I just doubt the plausibility of a “goldilocks” short that manifests itself as a consistent, fast blink.

This is interesting. The last time I had a turn signal bulb burn out was on a 2006 Chevrolet Uplander and the blinker rate increased. However, I remember that on my 1965 Rambler, when a turning signal bulb burned out, the remaining light didn’t flash at all but just remained on constantly. I also remember that when I pulled a trailer, the trailer lights caused the flasher to blink the lights too rapidly and I had to substitute a heavy duty flasher.
I still think a short to ground, no matter which system is used, would blow the fuse. I was pulling a U-Haul trailer with the Rambler and the trailer wiring had a short to ground. When I turned on the left signal, the fuse blew immediately.

Grr…ok, OK!

You got me running out to pull a bulb on my truck and see what happens. I replaced the flasher unit, so I KNOW it’s an old school, mechanical unit.

From observation, though (and I could be wrong) old school flashers flash more slowly on battery volts, whereas new ones have a constant rate, leading me to believe new school is done solid-state, with a manufactured “blink-a” noise.

I do know that the “fast blink” indicates a low current draw on modern cars, presumably as an indicator of a defective bulb.

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The difficult part about discussions like this is that it’s easy for them to get contentious. If we had the same discussions in a garage somewhere, we could happily disagree, learn from each other, joke about it, and enjoy the discussion.

if you replaced the bulb and no change check the socket

@JoeMario…if the bulb is working there will be a load (resistance) which will slow down the blinker. If that load is missing (blown bulb) then the steel strip that controls the blinking will cool down quicker causing the blinker to cycle quicker.