Audi A4 2.5TDI RB4 Tacho needle jumping

[budG60]

Hi, I am struggling with a RB4 tacho of an Audi 2.5tdi. The speed meter needle seems to work fine upto 30km, but then starts to jump. The signal is coming from the automatic gearbox and when reading the speed from it with vcds it is fine. I have swapped the needle motor, but no difference and when controlling the needles with vcds all is fine. Any ideas where the problem might be coming from?

[Daniulis]

I had similar problem on Passat B5+, just diference in gauges, there was same problem in tacho gauge, was jumping when it was going up, and no jumping when was failing down. Problem was, china xenon HID installed in headlamps, and no diference lights was on or off. Just after disconecting balasts needle came back to normal.