Left Indicator Flashing Too Fast Mk1 Focus

[Grotty]

hi all

my left indicator is flashing too fast all of a sudden. The back bulb has now blown which i put down to it being over worked. I've only just checked the blown bulb so i'm not sure if replacing it will balance the system out, perhaps the front is getting too much voltage causing the fast blinking but i would say probably not. When the hazards are on everything works fine (minus blown bulb)

Does anyone know what it might be?

thanks in advance

[martyntdci]

change ya bulb dude.......

[artscot79]

when it flashes fast thats a warning that one of the bulbs isnt working

[Grotty]

change ya bulb dude.......

yeah i know i cant get one until tomorrow. could it be that? ...

oh wait ok thanks artscot and Martyn...

is that in the handbook artscot?

[artscot79]

it might be in the handbook pretty sure it is all cars do it mate when one bulbs out the other flashes faster to le you know some have a warning on the dash computer mk1 focus just flashed faster mk2 does as well and gives a warning message

[Stoney871]

Definitely flashing faster due to the blown bulb.

Replace it and you'll be fine.

Afaik all cars do this.

[jeebowhite]

Or flashing faster possibly due to led bulb in The circuit :-) unlikely but these things can happen.

[mixmasterlooney]

James is correct LED Bulbs can create this reaction too but tbh you've already established there is a blown bulb and that is what causes the problem obviously.

The indicator lights are on closed circuit, each bulb creates a load on the circuit that load decreases/increases the voltage and amps to a pre-configured amount based on cable sizes, resistance etc, whenever a bulb has blown the resistance on the circuit decreases and the voltage increases causing the bulbs to flash faster and brighter.

If you were to add more bulbs to the same circuit the resistance would increase and voltage decrease causing all bulbs to flash slower with less lumens.

LED Bulbs generate less load than the equivalent halogen bulb and can give the impression of a missing bulbs in the circuit

[mjt]

whenever a bulb has blown the resistance on the circuit decreases and the voltage increases causing the bulbs to flash faster and brighter.

If you were to add more bulbs to the same circuit the resistance would increase and voltage decrease causing all bulbs to flash slower with less lumens.

Actually it's t'other way round - since the bulbs are wired in parallel when one blows the resistance in the circuit increases and the current decreases. Adding more in parallel would decrease the resistance and increase the current.

In the days when I first started driving the flasher units were simple bi-metallic units so the flashing speed was directly related to the current passing through the unit. A higher current would make the bi-metallic strip deflect further and take longer to return thus slowing the rate. A lower current would deflect it less and it would return more quickly. That's where the idea of rapid flashing when a bulb blew originally came from. Modern units are electronic so I'm guessing this has been deliberately designed-in.