Your English can't sux more than mine

My Mandarin speaking is near perfect however, then include my native French and you get Scottish mixed with Norwegian English out lolll
Didn't know you had an issue with your own light, sorry bud. Link me up if you have a dedicated thread.
Litronics goes off on bumps = bad connection/connector.
If really there are no indication visually of a bad connector and the circuit have continuity
while car parked, then a safe and quick alternative is to fabricate yourself a very bright 12v test light with extra long leads (so you can have it in-car) and hook it up to various stage of your headlight +/- circuit.
Have that test light next to you in the car and go back to the bump that normally take out your Lit Markus.
If you suspect the car's circuit start at the fuse. If you suspect the Litronic unit itself, then start at the headlight connector pins. That way you'll be able to identity which side the problem is coming from. Then take it from there.
You may find out that the electronics gets weak with time in the litronic unit itself Due to heat-cycles and vibrations (weaken conn, un-tighten connectors, etc). If original from factory then I wouldn't rule this out too quick - they are old. The fact that only the left side is affected leads me to believe it is the litronic headlamp itself or the connectors anywhere between the fuse and the headlamp.
A faulty light switch would cancel both your litronics