500 light arrangement

[rj1986]

Wonder if anyone can help me with the gf's car.

Both DRLs are gone and on my replace list.
But i also saw one of her sidelight was gone (just above the DRL in the same cluster)
But when she parked up, it turned back on.
So when engine off= 2 sidelights
Engine on = 1 side light.

So i thought it was to do with the DRL's being on, so when your engine is on, it turns off your sidelights. But surely it would turn both sidelights off.

Im assuming the DRL's are the lower bulbs in the set- the capless ones.
TIA

[rj1986]

Nevermind- worked it out- they're dual filament.
DRL's both work when engine is off/ lights off.
When you switch the light on, the larger filament comes on as a side light. And one of these have gone hence no light at all.