I've just noticed that the front drivers side sidelight on my 2016 Citigo doesn't come on when I'm on sidelights, but does when I turn the headlights on - what might that be?

I think they're dual filament, if so yours are goosed. 

Does your car have DRLs - it probably does? i.e the front "sidelights" being on all the time with ignition on?

Twin filament bulbs - on DRLs should be the bright filament, on sidelights should be the same (but tail light are on too), but when using  headlights, the dimmer filament should be on (and the same with parking lights, both sides but with L or R selectable using the indicator stalk).

 

Please post results for all combinations to help pinpoint the fault....

The working one is on all the time, and doesn't seem to change when I go to sidelights. I can't really tell the difference when the headlights are on. Could it be that just one of the the two filaments has gone, and so it just needs a simple bulb replacement?

 

57 minutes ago, carlwark said:

Could it be that just one of the the two filaments has gone, and so it just needs a simple bulb replacement?

Yes.

 

Thanks. AG Falco

Maybe, but the bulb should be at half brightness when the headlights are on. Hence we need the "truth table" of all the switch positions and bulb brightness results. But why not try a new bulb? It's cheap enough....

Edited 14 September, 20241 yr by freemansteve

Swap them from side to side always helps.

 

Thanks AG Falco