Possibly odd tail lights behavior

[WeekendDriver]

Hi. I was fiddling with my tail lights yesterday and found an oddity; please educate me as to whether it's normal or not. When I turn the position lights on, the smaller 5W bulb comes on, which is expected. But also, one of the big 21W bulbs is lit dimly, the one that's located in the outer bottom corner of the light (i. e. bottom left in the left light, bottom right in the right one). Is that normal? Note that mine is a EU car.

And another related question. I started getting a rear right fog light bulb error yesterday, but I checked the bulb it and it's OK. I have replaced the whole tail light with another one (which I do have), and it still doesn't work. So I'm led to believe there's something wrong with the wiring. I'll have to disassemble half the car to fix it, won't I? :( Is it even fixable?
Now back to the question number one: I wonder if both bulbs come on because the electrics controller thinks not all bulbs are working and it's some kind of fallback.

[ADCS]

Normal. The brake light is dimly lit to prolong the bulb life (This pre-warms the bulb to avoid giving a cold bulb full voltage when you tap the brakes).

[WeekendDriver]

Neat! Thanks, that's one less problem to worry about. Now if only I could find the cause of the right rear fog light malfunction...

[diagnosticator]

Neat! Thanks, that's one less problem to worry about. Now if only I could find the cause of the right rear fog light malfunction...

You can measure the de energized circuit resistance between the fog lamp socket and the Central Electric controller at the controller harness connector terminal pin, for a high circuit resistance or short to chassis ground. the voltage at the lamp socket can't be used to diagnose because the lamp is driven with a PWM voltage from the CECM, and will show a lower voltage than a regular lamp power circuit. Measuring open circuit voltage also won't help because the high input impedance of a DVM will trigger the lamp fault indication with a reduction of applied lamp voltage.

For a B6, the right fog lamp socket is not connected to anything and is unpowered. (If you are installing a B7 CECM, a resistor needs to be added to replace the missing fog lamp on the right side. This is because of the lamp socket base plate configuration in the tail lamp assembly.)

[WeekendDriver]

Wait a moment, did you just say the rear right fog light is never supposed to work on B6?

[MoparFreak69]

The only B6 cars that have a factory configured RIGHT rear fog lamp are RHD cars. In the case of these cars they will ONLY have a RIGHT rear fog bulb and NOT a left rear one.
Easy way to remember it is pre B7 cars only have a driver's side rear fog light as configured from the factory.

[WeekendDriver]

Ah! That explains why the right light housings have this section and a bulb, and why my aftermarket LED lights also have fog light section on both sides. It's just to unify them and make them fit both LHD and RHD cars. Thanks a lot!
It did occur to me I'm lucky that the malfunction is on the passenger side :)

Do you think this inert bulb is still being tested by the CIC regardless of the wheel placement side? In other words, could the error have, in fact, been caused by a faulty bulb? The error seems to be gone after my fiddling, I'm just not sure if for good.