The Medway Handyman gurgled happily, sounding
much like they were saying:

I though vehicle lights either worked or didn't?

Did you try the indicators & brakes at the same time, with and without
the lights on?

Especially with dual-filament bulbs, a ropy earth can lead to all sorts
of strangenesses if there's a dodgy earth - usually seen as Xmas Trees
when coincidental paths to earth via other circuits start to run out.