Problems after soldering the instrument cluster

Hello together!

I'm currently revising my instrument cluster completely and I have a little problem here, which has made me despair for 5 days. Maybe some of you can give me a tip where to look.

So, I opened the AI and soldered everything completely (resistances, diodes,...) on the two-part board and also exchanged the 5 Elkos. The little guy who's in charge of the car check was out a while ago. This was now the reason to solder everything again, to change the E15 gear, etc.

Now that I soldered the two-part Auto-Check board, the small "Huckpack-Platine" and changed all the pears, I wanted to see if I was successful in the car.

Hurrah, the car check is on again, only all the pears around the speedometer remain dark when I turn on the lights. The on-board computer also only provides me with the travel time and the rest range but no more consumption.

It is also used as a light source. flashes the airbag lamp. But I have already read here that this burns if you turn on the ignition without AI. Is that correct?

Ask the experts: In which corner should I look for the error? There could only have been a little bridge when soldering somewhere, right? Has anyone happened to encounter this mistake before?

On this small board, which is plugged onto the Auto-Check board, there is a two-pin connection on the back. Is it normal that I can't find a plug for this? Is it empty?

Everything else is running: Tacho runs and counts, DZM goes, outside temperature goes, gear indicator goes if you don't turn on the headlights, tank indicates correctly, oil pressure Ok, clock runs,...

I am grateful for all the clues!

Greeting Sebastian