2008 GS450h -BOTH High-Beam Headlights just stopped working!

[GS450hSE]

On my 2008 GS450h, owned for six years - BOTH High-Beam Headlights just stopped working simultaneously and without any warning. I noticed it when driving and I tried to use them. The bright blue dashboard light indicator for the main beam comes on, and there is no warning message on the dash. But those headlights aren't working (all the others are).

Easy, you say - their shared fuse must have blown.

Per the manual, both paper and online versions, one 20A fuse in the engine compartment fuse box handles both L & R main beam lights. So, I went to replace it:


From the instruction manual

To my shock, the corresponding fuse (20A) was perfect, and tightly seated. Continuity-checked with a multimeter. In case the wiring didn't correspond to reality, I checked all the fuses around - all were also OK.

So I whipped out my OBDII scan tool app on my mobile (BlueDriver gizmo plugged into the vehicle's OBDII port), but no error code of any kind shows up.

The only odd thing I can think of is, in the last year, and only a couple of times - the car is driven thrice a day on average - the left dipped beam light did not come on, but came on when I gave the outside of the housing a thump.

Please, what do I do next?

I've heard there is a relay in the circuit, perhaps shared between the L and the R high-beam lights.  Could this be the culprit - and where is it located?